PHYSICAL 


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fy^  a  $ 

Clb 


BAILEY' 


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cop. g  Bailey- 
Inductive  element- 
ary  physical 


pensive  apparatus 


Southern  Branch 
of  the 

University  of  California 


Los  Angeles 


Form  L  1 


K 


This  book  is  DUE  on  the  last  date  stamped  below 


Form  L-9-15ro-8,'26 


Experimental  Science  Series 


INDUCTIVE 

ELEMENTARY  PHYSICAL  SCIENCE 


INEXPENSIVE  APPARATUS,  AND  WITHOUT 
LABORATORY  EQUIPMENT 


BY 

F.   H.   BAILEY,  A.M. 

I   PANORAMA   OK   THE    HEAVENS,"  THE   "  CoSMOSl'HEKE," 


BOSTON,  U.S.A. 

D.    C.    HEATH    &    CO.,    PUBLISHERS 
1897 


COPYRIGHT,  isos  AND  : 
BY  F.  H.  BAILKY. 


TYPOGRAPHY  BY  C.  .1.  PETERS  A  SON,  HOSTON. 


PRBSSWORK  BV  KOCKWELL  &  CIHKCHILL. 


QC  'i.O 


.2 

PREFACE. 


THE  course  in  Elementary  Physical  Science,  of  which 
these  pages  form  the  first  instalment,  is  the  outgrowth  of 
various  experiments  made  first  in  the  public  schools  of 
Michigan,  later  in  Dr.  Felix  Adler's  Workingmen's  School 
in  New  York  City,  and  finally,  during  the  past  four  years, 
in  the  private  school  of  Mrs.  Quincy  A.  Shaw  in  Boston, 
—  a  school  founded  by  Mrs.  Shaw,  the  daughter  of  the 
great  naturalist,  Professor  Louis  Agassiz,  for  the  purpose 
of  developing  methods  of  nature  study  that  will  secure  to 
the  young  student  the  best  preparation  for  holding  through 
life  intimate  converse  with  nature. 

The  endless  source  of  happiness  which  this  gives  is  a 
heritage  that  Mrs.  Shaw  has  l>elieved  will  come  always  to 
all  students  who  are  introduced  to  the  study  of  the  earth 
by  the  natural  method.  The  author's  educational  views 
were  so  fully  in  accord  with  her  own,  that  she  gave  him 
perfect  liberty  in  laying  out  the  work  in  the  Physical 
Science  branches  of  nature  study  for  pupils  from  twelve 
to  eighteen  years  of  age.  The  results  reached  have  been 
such  that  many  of  the  best  educators  of  Boston  and  vicin- 
ity have  recommended  and  urged  that  the  course  be  given 
a  wider  field  of  usefulness. 

While  this  work  has  been  largely  the  result  of  class- 
room experiment,  indebtedness  is  freely  acknowledged  to 
Hi 


iv  PREFACE. 

various  sources,  especially  to  the  excellent  little  manual 
on  "  Home-made  Apparatus,"  by  Professor  John  F.  Wood- 
hull,  of  the  New  York  Teachers'  College. 

For  any  testimony  that  may  be  wished  in  regard  to 
the  merit  of  the  course,  the  following  are  referred  to :  Mrs. 
Quincy  A.  Shaw,  Boston,  Mass. ;  E.  Bentley  Young,  Mas- 
ter of  the  Prince  School,  Boston ;  Charles  F.  King,  Master 
of  the  Dearborn  School,  Boston ;  W.  A.  Mo  wry,  President 
of  Martha's  Vineyard  Summer  School ;  S.  T.  Button, 
Superintendent  of  Brookline  Schools;  Larkin  Dunton, 
Head  Master  of  Boston  Normal  School;  A.  E.  Winship, 
Editor  of  The  Journal  of  Education  ;  and  Frank  A.  Hill, 
Secretary  of  Massachusetts  Board  of  Education. 

F.   H.   B. 

6  MARLBORO  STREET,  BOSTON,  MASS. 
January,  1895. 


CONTENTS. 


PAGE 

PREFACE iii 

To  THE  TEACHEK  CONCERNING  :  — 

THE  COURSE vii 

APPARATUS,  IN  GENERAL xi 

APPARATUS,  HOME-MADE xiii 

APPARATUS,  PROVIDED  BY  THE  AUTHOR xvii 

ADDITIONAL  APPLIANCES xviii 

Tin:  LABORATORY xx 

PREFACE  TO  SKCOND  EDITION      . xxiii 

AUXILIARY  WORK       xxiv 

QUANTITATIVE  WORK xxvi 

METHODS  OF  CONDUCTING  THE  WORK xxvi 

LETTER  FROM  PRINCIPAL  E.  B.  YOUNG xxix 

LETTER  FROM  AUTHOR  TO  PUPIL 1 

STUDY  OF  APPARATUS,  ILLUSTRATED 5 

DIRECTIONS  FOR  ADJUSTING  "100  IN  1" 10 

WATER  EXPERIMENTS 18 

AIR  EXPERIMENTS 30 

QUANTITATIVE  AIR  EXPERIMENTS 52 

BUOYANCY  EXPERIMENTS 61 

SPECIFIC  GRAVITY  EXPERIMENTS 64 

DENSITY  EXPERIMENTS 08 

VOLUME  BY  WEIGHING 70 

AUXILIARY  WORK 71 

APPENDIX       100 

"  100  IN  1  PHYSICAL  SCIENCE  APPARATUS  "    .     ...  106 


TO    THE    TEACHER. 


No  previous  knowledge  of  physics  is  absolutely  neces- 
sary ;  but  a  clear  conception  of  the  object  aimed  at  is  im- 
perative, in  order  that  the  work  may  be  done  in  a  scientific 
manner,  and  the  highest  success  attained.  That  object  is 
not  primarily  to  give  the  pupil  a  few  physical  facts  out  of 
the  great  abundance  of  truth,  a  few  essentials  of  which  is 
all  that  is  possible  in  any  course,  but  to  cultivate  his  pow- 
ers of  observation  and  independent  thought.  Every  young 
child  possesses  these  powers,  and  is  eager  to  use  them ; 
but  a  system  exclusively  of  book-education  tends  to  de- 
stroy them.  Some  one  has  truthfully  said,  "  No  injustice 
would  be  done  to  a  teacher  if  his  skill  and  the  educative 
value  of  his  lessons  were  measured  by  his  success  in  mak- 
ing children  reason  out  conclusions  from  okserved  or  stated 
facts ;  "  and  we  may  add  that  for  the  best  discipline  those 
facts  should  be  observed,  not  stated.  That  education  is  of 
the  most  value  in  every  walk  of  life  wlfich  not  only  enables 
its  possessor  to  reason  correctly  upon  facts  possessed,  but 
which  gives  him  the  power  of  keen  and  accurate  observa- 
tion by  means  of  which  to  collect  the  facts  for  himself. 
Seeing  is  not  so  simple  an  act  as  many  suppose.  Every 
scientist  knows  that  it  is  one  thing  to  turn  the  eyes  towards 
an  object,  but  quite  another  thing  to  see  what  is  there. 
Every  one's  observational  powers  need  cultivating,  and 


viij  TO   THE  TEACHER. 

"  Observation  Lessons  "  are  of  value  for  this  purpose,  but 
doubly  valuable  when  so  arranged  as  to  become  an  incen- 
tive to  logical  reasoning. 

In  planning  this  course  these  two  objects  have  been  kept 
in  view,  and  they  should  be  continually  before  the  teacher 
in  charge.  If  the  course  is  properly  taught,  pupils  who 
have  been  in  the  habit  of  learning,  or  trying  to  learn,  with- 
out independent  thought,  find  that  it  is  impossible  to  do 
so  in  this  work.  They  are  compelled  to  use  their  eyes  in 
collecting  facts,  to  put  these  facts  together,  and  to  draw 
conclusions  from  them.  These  processes  at  their  com- 
mand, they  are  then  prepared  for  the  great  school  of  life ; 
but  without  having  acquired  these  processes,  no  amount 
of  accumulated  facts  are  of  much  value.  Teachers  who 
have  never  tried  this  method  will  be  astonished  at  the  ease 
with  which  children  adopt  it.  At  first,  if  their  previous 
instruction  has  been  entirely  by  the  memory  method,  this 
one  seems  to  fail  completely.  The  pupils  can  use  neither 
hands,  eyes,  nor  minds.  They  cannot  experiment  success- 
fully, nor  see  more  than  a  small  part  of  what  happens  when 
the  experiment  is  done,  to  say  nothing  of  thinking  out 
what  it  all  means.  But  I  have  not  yet  had  a  pupil  whose 
habit  of  leaning  upon  book  or  teacher  was  so  strong  that 
it  did  not  give  wa^  within  a  brief  space  of  time,  and  let 
some  degree  of  self-activity  show  itself.  In  training  the 
pupil  to  self-reliance,  it  is  at  the  very  beginning  that  the 
skilful  teacher  has  the  opportunity  of  doing  his  l>est  work. 
I  have  tried  several  methods :  one  extreme  is  to  assist  the 
pupils  in  every  step  at  the  beginning,  and  wean  them  grad- 
ually ;  the  other,  to  throw  them  entirely  upon  their  own 
resources  from  the  very  beginning.  Of  the  two  extreme 


TO   THE  TEACHER.  IX 

methods  the  latter  is  the  better,  provided  the  pupil  can  be 
prevented  from  becoming  discouraged  before  he  gets  a 
start. 

The  particular  method  in  which  you  conduct  your  class 
will,  of  course,  depend  upon  circumstances.  Only  general 
directions  can  be  given.  Though  you  have  no  teaching  to 
do,  that  being  done  by  Nature,  the  best  of  all  teachers, 
nevertheless  you  should  teach  (if  we  may  use  the  paradox) 
by  the  most  successful  method  —  that  of  example.  Be  a 
student  of  nature  with  your  class,  and  acknowledge  your- 
self such.  Have  a  set  of  the  apparatus,  try  the  experi- 
ments, and  write  your  inferences  just  as  your  pupils  do, 
either  at  the  same  time  or  previously.  You  will  become 
interested  in  the  work,  and  that  interest  will  spread  to 
every  pupil.  That,  at  least,  has  been  my  experience. 
Children  are  imitative ;  and  when  they  see  you  doing  and 
enjoying  interesting  experiments,  they  will  wish  to  do  them 
also.  At  the  same  time  you  can  easily  appeal  to  another 
element  which  is  still  stronger  in  most  children  —  that  of 
emulation ;  not  an  unworthy  incentive  to  appeal  to,  espe- 
cially if  it  is  done  with  skill.  They  will  compare  their 
inferences  one  with  another.  Get  them  to  compare  with 
yours.  You  should  also  examine  their  written  work,  and 
commend  all  of  it  that  shows  independent  effort.  Fre- 
quently you  can  commend  pupils  for  their  discoveries, 
at  the  same  time  that  you  criticise  their  statements  of 
facts.  Always  commend  when  you  can,  and  criticise  with 
moderation. 

There  is  no  better  way  to  become  acquainted  with 
your  pupils,  and  no  better  opportunity  for  doing  individual 
work.  It  is  sometimes  claimed  that  it  is  impossible  to 


X  TO   THE  TEACHER. 

individualize  with  the  pupils  in  our  public  schools  when 
the  classes  are  large ;  but  by  this  method  it  becomes  com- 
paratively easy.  After  school  you  have  in  your  possession 
the  notes  written  during  experiment  hour;  and  through 
them  you  rapidly  become  acquainted  with  your  pupils, 
and  see  just  how  you  can  best  help  them.  Frequently 
they  need  no  help,  with  the  exception  of  some  brief  marks 
agreed  upon  to  indicate  the  mistakes  you  wish  them  to 
correct.  Some  pupils  may  need  a  word  of  encouragement 
or  direction ;  and  this  is  usually  more  valuable  if  given  in 
writing,  though  sometimes  it  is  better  to  speak  to  them 
privately.  Seldom  speak  to  a  pupil  in  class,  unless  it  is 
in  a  whisper;  for  the  class-hour  should  be  a  silent  one  on 
the  part  of  teacher  as  well  as  pupils.  If  you  would  have 
it  quiet,  keep  quiet  yourself. 

For  suggestion  for  correcting  books  or  papers,  see  note 
to  "  Author's  Letter  to  Pupils."  This  method  of  studying 
science  furnishes  one  of  the  best  opportunities  for  discipline 
in  English  composition  ;  for  pupils  have  something  to  write 
about,  consequently  essay-writing  becomes  easy  and  pleas- 
urable, and  pupils  form  the  invaluable  habit  of  writing 
upon  subjects  about  which  they  know  something,  and  of 
expressing  their  own  thoughts  and  discoveries.  In  fact, 
the  many  incidental  benefits  derived  from  the  course  are 
of  more  value  than  even  the  physical  knowledge  gained. 
Moreover,  aside  from  the  particular  physical  facts  that  the 
pupil  discovers,  there  are  general  ones  of  much  greater 
value,  which  can  neither  be  understood  nor  appreciated  un- 
less reached  through  the  individual  experimental  method ; 
such  as  the  fact  that  the  answers  obtained  from  nature 
depend  upon  the  questioner ;  that  they  approach  the  truth 


TO   THE   TEACHER.  XI 

in  proportion  as  the  question  is  properly  put,  and  the  an- 
swer carefully  read ;  the  immutability  of  the  operation  of 
nature  —  the  fact  that  exactly  the  same  causes  always  pro- 
duce exactly  the  same  results ;  the  fact  that  there  is  no 
such  thing  as  chance,  every  effect  having  its  cause ;  the 
fact  that  the  so-called  "  natural  laws  "  are  simply  our  ex- 
planation of  nature's  uniform  operations.  By  this  method 
of  study,  as  one  of  our  critics  has  put  it,  "  the  pupil  comes 
to  see  things  as  they  are,  and  not  as  he  thinks  they  ought 
to  be." 

APPARATUS. 

Of  no  less  importance  than  the  outline  of  the  course 
in  physics  is  the  apparatus  with  which  the  experiments 
are  performed.  To  meet  the  wants  of  grammar  schools, 
the  apparatus  should  be  neither  extensive  nor  expensive, 
but  it  should  be  sufficient  and  of  an  interesting  character. 
In  order  to  obtain  from  it  the  best  discipline,  not  only 
should  the  apparatus  itself  be  carefully  considered,  but 
the  means  by  which  it  is  provided.  Theoretically,  the 
plan  for  using  home-made  apparatus  is  the  best ;  but  this 
plan  has  usually  failed  to  be  very  satisfactory  in  practice, 
because  of  the  crudeness  of  the  method  by  which  it  was 
attempted.  Pupils  will  do  much  in  the  line  of  making 
their  own  apparatus  after  they  have  become  interested  in 
the  work,  but  generally  not  at  first. 

We  have  found  it  the  best  plan  to  provide  the  pupil 
at  the  beginning  with  simple  apparatus  for  trying  interest- 
ing experiments ;  then  to  lead  him,  after  his  interest  in 
experimental  science  is  aroused,  to  increase  his  stock  by 
such  pieces  as  he  can  easily  make  for  himself.  No  matter 


xii  TO   THE  TEACHER. 

how  simple  it  is,  he  takes  more  interest  in  experimenting 
with  apparatus  provided  for  the  purpose,  especially  if  it  is 
of  his  own  make,  than  in  using  articles  not  set  apart  or 
especially  fitted  up  for  his  purpose. 

Interest  the  pupil  in  experimental  science ;  then  pro- 
vide him  with  files  and  a  little  glass  and  rubl>er  tubing, 
and  he  will  find  his  own  cans  and  bottles,  and  make  his 
own  apparatus.  We  have  seen  this  method  produce  such 
excellent  results  that  we  cannot  too  earnestly  recommend  it. 

In  order,  however,  to  adapt  this  work  to  the  widest 
possible  range  of  conditions,  it  is  published  in  two  parts  — 
the  "  Elementary  Physical  Science,"  and  the  "  Auxiliary 
Work."  The  first  part  is  complete  in  that  it  brings  out 
every  essential  principle  of  the  subjects  treated.  This, 
together  with  the  apparatus  which  we  provide,  is  adapted 
to  such  schools  as,  for  any  reason,  cannot  adopt  the  home- 
made apparatus  plan. 

The  "Auxiliary  Work"  consists  of  clearly  illustrated 
directions  for  making  extra  apparatus  for  experiments 
which  will  be  found  useful,  either  to  bring  out  the  princi- 
ple sought  in  a  different  and  more  striking  manner,  or  to 
furnish  interesting  applications  of  laws  already  learned. 

To  make  applications  is  as  essential  in  the  study  of 
physics  as  in  arithmetic ;  and  for  that  purpose  a  variety 
of  experiments  is  better,  and  far  more  interesting  to  the 
pupil,  than  a  number  of  problems.  In  a  very  few  cases 
(two  or  three  only,  in  this  first  course),  where  applica- 
tions by  experiment  are  not  practical,  problems  are  given. 

Another  benefit  afforded  by  the  "  Auxiliary  Work  ".  is 
that  it  furnishes  an  easy  entering  wedge  for  manual-train- 
ing work,  the  value  of  which  is  now  conceded  by  our  best 


TO    THE   TEACHER.  xiii 

educators.  Whenever  it  is  possible,  pupils  should  be  per- 
mitted, or  even  required,  to  make  their  own  apparatus. 
Except  the  drilling  of  holes  in  glass  bottles,  it  can  be 
readily  done  —  even  this  is  not  so  difficult  as  at  first  it 
seems ;  it  has  been  repeatedly  done  by  the  younger  pupils 
of  the  author's  classes.  Not  only  does  the  pupil  take 
more  interest  in  performing  the  experiments  with  appara- 
tus of  his  own  making,  but  he  is  at  the  same  time  training 
the  hands  as  well  as  the  mind.  Moreover,  there  is  a  fasci- 
nation in  the  endeavor  to  acquire  precision  in  either  wood 
or  in  metal  working  —  there  is  an  especial  fascination  in 
the  manipulation  of  glass  designed  for  apparatus.  Pupils 
have  willingly  devoted  most  of  their  leisure  time  to  such 
work  —  with  the  broken  ends  of  three-cornered  files,  drill- 
ing holes  in  thick  glass  bottles  —  making  them  true  with 
rat-tail  files  —  bending  and  blowing  glass  tubing  —  in 
fact,  themselves  making,  from  beginning  to  end,  apparatus 
capable  of  use  for  fairly  precise  quantitative  results. 
They  did  not  always  exactly  reproduce  things  they  had 
seen,  but  exercised  their  inventive  powers,  and  occasion- 
ally produced  something  new.  Thus  these  young  pupils 
became  not  only  discoverers  in  the  field  of  physics,  but 
genuine  inventors  ;  and  they  obtained  a  better  education  by 
such  efforts  than  book  study  alone  could  ever  have  given 
them. 

DIRECTIONS    FOR    OBTAINING    MATERIAL    AND    MAKING 
APPARATUS. 

Illustrated  instructions  in  glass-working  that  will  be 
useful  to  all,  whether  provided  with  the  regular  apparatus 
or  not,  are  given,  under  the  heading  of  "  Auxiliary 


xiv  TO   THE   TEACHER. 

Work ;  "  but  a  few  preliminary  directions  will  be  espe- 
cially helpful  to  those  who  make  all  their  own  apparatus. 
The  body  01  the  "  100  in  1  "  apparatus  may  be  made  of 
almost  any  wide-mouthed  bottle.  The  most  difficult  part 
of  the  work  lies  in  making  the  holes.  I  know  of  but  one 
way  that  is  generally  practicable  for  the  student,  and  that 
is  the  one  mentioned  above  as  used  by  my  own  pupils. 
Holes  may  be  made  with  a  hard  steel  drill  held  in  a  car- 
penter's brace;  but  the  drill  requires  •frequent  sharpening, 
and  the  novice  will  break  more  "bottles  than  when  using  a 
broken  file  held  in  the  hand.  In  some  localities  machin- 
ists can  be  found  who  will  drill  them.  It  is  claimed  that 
glass  is  more  easily  drilled  when  wet  with  turpentine  ;  but 
I  find  that  water  does  just  as  well  either  with  file  or  drill, 
and  I  have  frequently  made  the  holes  with  files  without 
using  any  liquid.  If  a  file  is  used  (and  an  old  worn-out 
one  is  just  as  good  as  any),  when  the  cornel's  become  dull 
lay  the  end  on  a  piece  of  iron,  and  break  off  the  end  with 
a  hammer.  After  a  little  practice  a  very  small  bit  at  a 
time  can  be  broken  off,  and  so  the  tile  can  be  used  for 
drilling  many  holes.  Hold  the  bottle  firmly,  and  be  satis- 
fied with  slow  progress,  especially  when  the  hole  is  nearly 
through. 

It  is  advisable  to  obtain  the  rubber  tubing  first,  then 
to  make  the  holes  just  the  size  for  it  to  fit  snugly.  The 
tubing,  obtained  from  druggists,  school-supply,  or  rubber 
dealers,  should  be  of  the  best  quality.  Nothing  is  more 
unsatisfactory  than  poor  rubber  for  the  short  pieces  that 
unite  glass  tubes  and  bottle.  For  that  purpose  even  the 
best  quality,  if  very  thin-walled,  does  not  work  well. 
Each  set  of  apparatus  requires  about  three  feet ;  and,  if 


TO    THE   TEACHER.  XV 

the  best  is  obtained,  the  short  pieces  can  be  cut  from  the 
long  one,  and,  if  lost,  easily  replaced.  One  inch,  how- 
ever, of  the  best  quality  and  thickness,  together  with 
three  feet  of  cheaper  tubing  (if  it  is  not  the  poor,  half-clay 
stuff),  will  answer  very  well.  The  soft  glass  tubing 
should  be  of  medium  thickness ;  for,  if  thin,  it  breaks  too 
easily  for  pupils'  use.  A  good  quality  is  furnished  by 
school-supply  dealers,  at  prices  from  fifty  to  seventy-five 
cents  per  pound.  The  glass  tubing  should  be  a  very  little 
larger  than  the  hole  in  the  rubber,  so  that  it  will  make 
the  connection  with  the  bottle  not  only  water-  but  air- 
tight, even  under  the-  pressure  of  two  or  three  atmos- 
pheres. As  the  glass  tubing  is  sure  to  vary  somewhat  in 
size,  select  carefully  that  which  fits  best  for  pieces  that 
are  used  in  bottle  holes.  Other  sizes  may  be  used  for 
Pressure  Gage,  Equal  Armed  Siphon,  Siphon  Fountain, 
etc. ;  even  the  pieces  to  be  used  in  the  stopper  may  vary 
more  than  those  in  bottle  holes.  The  latter  should  not 
vary  a  thirty-second  of  an  inch  in  order  to  work  well. 
The  variation  may  be  greater,  however,  with  thick  than 
with  thin  rubber  connectors  or  packing. 

Corks,  if  of  the  best  quality,  may  be  used  quite  suc- 
cessfully for  most  of  the  experiments,  though  rubber 
stoppers  are  much  better.  If  corks  are  used,  soften  by 
rolling  them  on  the  floor  with  the  foot,  using  considerable 
pressure,  after  which  make  the  holes  with  a  rat-tail  file, 
if  not  provided  with  regular  cork-bore  re.  If  rubber  stop- 
pers are  used,  get  the  best ;  though  the  difference  in  price 
of  rubber  stoppers  is  considerable,  it  is  not  comparable 
with  the  difference  in  satisfaction  afforded,  and  the  best 
will  last  much  longer  without  becoming  hard.  We  have 


TO   THE   TEACHER, 


been  using  some  for  four  years  that  are  yet  excellent; 
and  others  that  were  very  good  at  first  are  now  so  hard  as 
to  be  utterly  worthless.     The  difference  in  the  length  of 
wear  of  rubber  tubing  is  even  greater  than  that  of  stop- 
pers.    We  have  four-holed  stoppers  of  the  best  shape  and 
material  made  on  purpose  for  the   work;    but  the   best 
quality  with  two  holes,  always  to  be  found  on  the  market, 
do  just  as  well  for  nearly  every  experiment,  provided  tli.-v 
fit  the  bottles  perfectly.     They  should  enter  but  a  very 
short  distance,  and  should  not  flare   enough  to  prevent 
being  crowded  in  nearly  their  entire  length.     Most  stop- 
pers flare  too  much  to  work  well   in  some   experiments, 
unless  the  neck  of  the  bottle  flares  nearly  as  much.     The 
holes  should  admit  the  glass  tubes  easily  when  the  stop- 
per is  not  inserted  in  the  bottle,  and  is  wet.     For  ili.-s,- 
reasons,  stoppers  and  rubber  tubing  should  first  be  se- 
lected, then  glass  tubing  obtained,  and  the  holes  in  the 
bottle  made  to  correspond.     Stoppers  of  the  same  make 
and  number  are   of    the  same   size,    but  not  so   are   the 
mouths  of  bottles  of  the  same  «  batch."     They  vary  more 
than  most  dealers  will  admit.     Hence  the  stopper  and  the 
bottle  should  be  seen  to  fit  perfectly  before  labor  is  ex- 
pended in  hole-making. 

If  you  collect  pickle  or  similar  bottles  (which  can  usu- 
ally be  done  cheaper  than  buying  from  dealers),  and  on  In 
stoppers  and  tubing  by  mail,  specify  that  the  outside  diam- 
eter of  the  glass  tubing  must  be  the  same  as  that  of  the 
hole  in  stopper,  and  the  diameter  of  hole  in  rubber  tubing 
a  very  little  less. 

We  give  below  the  price  and  number  of  the  best 
two-holed  stoppers  furnished  by  the  Franklin  Educational 


TO    THE   TEACHER. 


Company  of  Boston,  for  the  smallest-mouthed  bottles  that 
are  convenient  both  to  obtain  and  to  use. 

No.  10,  price  45  cents,  is  a  trifle  too  large,  and  No.  9 
is  not  large  enough,  for  a  l|-inch  hole,  but  just  right  for 
sizes  between  1]  and  1|  inches.  Fronj*l$  to  !T7g,  No.  11, 
price  50  cents.  From  li  to  If,  No.  12,  price  55  cents. 
No.  12  is  exactly  l.V  inches  diameter  at  the  smaller  end, 
hence  will  not  work  well  for  all  experiments  in  a  l|-inch 
mouth,  but  will  for  one  a 
trifle  more  or  less  than  Ijj. 
These  stoppers  have  holes 
the  same  size,  namely,  j  inch 
diameter ;  No.  9  has  smaller 
holes.  Price  of  an  excellent 
rubber  tubing  to  fit  J-inch 
glass  is  8  cents  per  foot ;  of 
the  very  best  (the  same  we 
use  and  furnish),  10  cents. 
The  same  size  tubing  can  be 
bought  for  1  cents,  being,  of 
course,  a  much  inferior  qual- 
ity. 

THE    "100   IN   1"    PHYSICAL 
SCIENCE   APPARATUS. 

In  order  to  meet  the 
wants  of  such  as  cannot 
make  all  their  apparatus,  we  F'9-  '• 

furnish    sets    at    the    lowest 

price  consistent  with  the  best  material  and  workmanship. 
Instead  of  bottles  with  drilled  holes,  we  have  devised   a 


Xviii  TO   THE   TEACHER. 

glass  cylinder,  the  ''Apparatus,"  which  is  much  better. 
This  is  shown  in  the  cut,  together  with  the  largest  num- 
ber of  attachments  used  for  any  one  experiment.  This 
cylinder  is  made  of  clear  pressed  glass  ;  consequently 
mouth  and  holes  4o  not  vary  in  size,  the  latter,  for  the 
easier  admittance  of  connectors,  flare  slightly.  It  is  5} 
inches  tall  (more  than  2J  times  that  of  the  cut),  Ig  inches 
in  diameter,  with  a  thickness  of  |  inch  at  the  top,  which 
increases  regularly  to  £  inch  at  the  bottom.  The  thick- 
ness of  the  bottom  (the  only  thing  which  can  vary,  and 
slight  variation  there  does  not  affect  its  utility)  is  from  | 
to  I  of  an  inch.  It  is  not  easily  broken,  usually  sustain- 
ing a  fall  from  table  to  floor  unharmed,  though  not  al- 
ways, depending  probably  upon  the  way  it  happens  to 
strike. 

ADDITIONAL  APPLIANCES   FOR   EACH  PUPIL  OR   SCHOOL. 

A  few  articles  easily  obtained,  differing  somewhat  ac- 
cording to  circumstances,  are  needed,  together  with  the 
regular  "100  in  1  "  apparatus.  A  dish  of  water  for  each 
pupil,  from  which  to  supply  the  Apparatus  or  bottle,  and 
in  which  many  of  the  experiments  are  performed,  is  the 
only  one  absolutely  necessary  under  all  conditions.  We 
mention  several  used  for  that  purpose,  that  choice  may  be 
made  according  to  circumstances.  A  somewhat  expensive 
thing,  but  the  best  for  private  schools  with  small  classes 
and  well-fitted  laboratories,  is  the  glass  battery  jar,  6  inches 
in  diameter  and  7  inches  deep,  illustrated  in  EXP.  11.  A 
cheap  substitute,  which  does  very  well,  in  fact  just  as  well 
in  most  experiments,  is  a  certain  make  of  fruit  jar,  5i 
inches  deep  and  &  inches  in  diameter,  with  a  mouth  of 


TO   THE   TEACHER.  xix 

3|  inches  in  diameter,  illustrated  in  EXP.  23.  Two-quart 
fruit-jars,  or  large  acid  bottles,  are  easily  cut  off  near  the 
top,  and  make  excellent  water-jars.  (See  easy  method  of 
cutting  bottles,  Auxiliary  Work.)  Probably  in  most  pub- 
lic schools  the  flaring  4-quart  tin  pail  shown  in  EXP.  12 
will  be  most  satisfactory. 

If  work  is  done  on  sloping  desks  with  lids,  blocks  to 
level  the  lids  are  better  than  books ;  if  desk-tops  are  sta- 
tionary and  slope,  blocks  are  necessary  to  level  a  tray  on 
which  to  experiment. 

A  tray  or  shallow  pan.  As  some  water  is  unavoidably 
spilled,  even  the  most  careful  pupil  will  usually  need  a 
pan,  unless  working  on  a  specially  prepared  laboratory 
table,  or  where  a  little  water  is  not  objectionable. 

Each  pupil  should  bring  from  home  a  tumbler  and  a 
small  towel,  and  keep  them  with  his  tin  pail  and  pan. 
These  four  are  all  the  extra  articles  needed  for  the  regular 
experiments. 

If  any  of  the  auxiliary  apparatus  is  made,  two  tools 
are  absolutely  necessary,  a  round  or  rat-tail  file  and  an 
awl.  With  these  each  pupil  can  make  for  himself  several 
valuable  additional  pieces  of  apparatus,  at  no  expense  in 
money  and  but  little  in  time.  Corks  for  extra  bottles  are 
easily  perforated  with  the  file,  so  that  tubes  of  the  regular 
sets  will  fit.  Small  tin  cans,  such  as  those  for  baking- 
powder,  spices,  etc.,  are  easily  obtainable,  and  can  be 
punched  with  the  awl  or  nail ;  then  the  hole  can  be  easily 
enlarged  with  the  file  until  the  tubes  fit.  With  the  rat- 
tail  file  holes  are  easily  made  through  the  "  edge  "  of  a 
bottle  ;  then,  with  care,  they  may  be  rounded  so  that  the 
rubber  tubes  will  fit  them.  Where  gas  is  available,  two 


XX 


TO   THE  TEACHER. 


other  files  should  be  supplied,  —  one  a  "  three-cornered," 
the  other  a  "  half-round  "  file.  A  gas-jet  bottle-cutter  is 
furnished  if  desired  but  a  file  is  needed  to  scratch  the  glass 
where  the  fine  gas-jet  is  to  cut  it,  and  the  half-round  file 
to  smooth  the  edges  so  that  they  will  not  cut  the  fingers. 
Keep  the  file  wet  when  in  use. 


THE   LABORATORY. 

It  is  now  conceded  that  the  laboratory  is  one  of  the 
first  essentials  of  every  well-equipped  school,  outranking 
in  importance  even  the  library.  The  education  there  ob- 
tained is  more  practical,  and  of  the  kind  to  which  civiliza- 
tion is  chiefly  imlebted.  That  the  laboratory  has  not 
found  its  way  into  every  school  is  due,  in  part  at  least,  to 
the  usually  great  expense  of  its  equipment  and  mainte- 
nance. It  is  believed  that  in  this  course,  for  one  so  valu- 
able, the  laboratory  expense  has  been  reduced  to  the 
minimum,  and  that  in  no  school  are  the  difficulties  in  the 
way  of  its  introduction  insurmountable.  Not  only  the  ap- 
paratus itself,  but  the  other  provisions  for  the  work,  may 
be  more  or  less  extensive,  according  to  conditions.  Pupils 
can  do  all  their  experimenting  at  home  on  the  kitchen 
table,  or  wherever  convenient.  It  can  be  done  on  ordinary 
school-desks,  in  trays,  or  shallow  pans,  levelled  with  blocks 
if  the  desks  slope ;  the  apparatus  when  not  in  use  being 
kept  in  the  boxes  stacked  in  the  corner  of  the  room,  or  on 
shelves.  In  most  schoolrooms,  there  are  one  or  more  walls 
against  which  narrow  tables  can  be  fastened  with  hinges, 
and,  if  in  the  way,  let  down  when  not  in  use,  the  cup- 
boards or  shelves  for  apparatus  being  placed  above.  If 


TO    THE   TEACHER.  XXI 

there  is  not  table  room  for  an  entire  class,  the  class  may 
work  in  sections  at  different  hours,  in  which  case  sets  of 
apparatus  for  one  section  is  all  that  will  be  needed.  It  is 
advisable,  however,  when  convenient,  that  a  room,  even 
though  small,  be  set  apart  for  laboratory  work.  Its  fit- 
tings need  not  be  elaborate,  tables  being  the  only  absolute 
necessity,  though  water  and  gas  are  exceedingly  conve- 
nient. Water  must  be  provided  in  some  way,  even  if  it  is 
brought  in  pails.  Gas,  or  the  Bunsen  Blast  Alcohol  Lamp, 
also  is  a  necessity  if  glass  apparatus  is  to  be  manufactured. 
A  jet  for  each  one  or  two  pupils  of  a  section  is  very  con- 
venient ;  though  much  may  be  done  with  but  one  jet  in  the 
room,  by  using  rubber  tubing  long  enough  to  bring  the  gas 
to  the  table,  where  it  may  be  connected  with  either  a 
common  or  a  Bunsen  burner,  or  the  glass-cutter,  according 
to  the  work  for  which  it  is  desired. 

Appliances  for  the  second  part,  which  continues  the 
study  of  air  and  water,  but  in  a  more  decidedl}r  quantita- 
tive manner,  differ  but  little  from  those  used  for  the  first, 
some  additional  apparatus  being  required  and  furnished, 
though  it  is  easily  made  by  the  teacher. 

The  study  of  heat  should  follow,  and  constitute  a  part 
of  that  of  air  and  water,  and  so  fit  the  pupil  for  the  study, 
either  in  or  out  of  school,  of  the  constantly  varying  phe- 
nomena of  the  seasons,  and  such  practical  subjects  us  house- 
heating,  ventilating,  etc. 

The  teacher  will  perceive,  by  examination  of  the  mate- 
rial selected  and  method  employed,  what  the  author  has 
learned  by  experience,  that  this  course  is  just  as  available 
for  high-  as  for  grammar-school  pupils.  It  is  for  the  be- 
ginner in  physics,  whatever  his  age  or  advancement  in 


xxii  TO   THE  TEACHER. 

other  studies ;  the  older  or  abler  pupils  can  do  more  com- 
plete work,  and  perhaps  accomplish  in  one  or  two  months 
what  would  profitably  occupy  others  for  a  year.  This 
great  elasticity  and  adaptability  is  one  of  the  strongest 
features  of  the  course. 


PREFACE   TO   SECOND   EDITION. 


THE  first  edition  of  this  book  was  issued  in  sheet  form, 
with  blank  pages  for  notes,  in  accordance  with  the  method 
pursued  by  the  author  in  the  school  where  the  work  was 
evolved.  The  persistent  demand  for  it  in  regular  book 
form  has  led  to  the  change.  The  author  has  embraced  the 
opportunity  to  make  several  revisions,  in  order  to  facilitate 
the  work  with  large  classes,  and  to  adapt  it  still  better  to 
the  capacity  of  grammar-grade  pupils  who  have  not  had 
previous  instruction  in  science.  Care  has  also  been  taken 
to  reduce  the  time  required  upon  the  part  of  the  teacher 
in  correcting  the  written  work. 

The  alterations  in  the  course  are  not  radical,  though 
they  considerably  improve  it,  especially  for  public-school 
use.  They  consist  of  the  introduction  of  an  illustrated 
list  of  the  pieces  contained  in  the  "100  in  1"  set  of 
apparatus,  to  aid  the  pupil  in  becoming  acquainted  with 
his  tools  and  their  names  ;  of  twenty  new  cuts  illustrating 
experiments ;  in  several  instances  of  more  explicit  direc- 
tions and  questions ;  of  the  omission  of  the  lever  experi- 
ment, and  all  applications  of  it  in  explanation  of  balancing 
forces  in  fluids,  and  the  substitution  of  EXPS.  5  and  6; 
of  some  slight  changes  in  both  experiments  and  appara- 
tus, to  avoid  the  necessity  of  a  pupil  ever  borrowing  of 
his  neighbor,  or  of  two  ever  having  to  work  together, 
xxiii 


xxiv  PREFACE   TO   SECOND   EDITION. 

The  latter  desideratum  is  reached,  and  two  very  pretty 
and  instructive  experiments  preserved  (Nos.  22  and  23), 
by  relegating  them  to  the  Auxiliary  Course,  in  which  case 
the  teacher  will  decide  when  and  how  they  shall  be  done, 
if  at  all.  They  may  he  omitted  altogether  if  necessary ;  as, 
like  most  of  the  Auxiliary  Experiments,  they  embody  only 
applications  of  principles  learned  in  the  regular  course. 
Aside  from  the  manual  training  their  construction  gives, 
and  the  increased  interest  aroused,  the  Auxiliary  Experi- 
ments are,  educationally,  of  about  the  same  value  as 
mixed  examples  in  arithmetic  introduced  at  the  proper 
time;  hence  the  list  might  be  abbreviated  or  entirely 
omitted. 

THE  AUXILIARY  WORK. 

The  Auxiliary  Experiments  are  placed  in  the  back 
part  of  the  book,  and  referred  to  whenever  they  would  be 
of  aid.  Every  reference  to  them  should  be  looked  up  by 
both  teacher  and  pupils,  as  frequently  some  help  can  be 
obtained  thereby,  even  Avithout  the  apparatus ;  but  of 
more  importance  is  the  fact  that  frequently  the  auxiliaries 
are  so  simple  that  the  pupil  can  easily  obtain  the  material 
and  do  the  experiments  at  home.  Those  requiring  glass 
tubing  should,  if  possible,  be  made  by  teacher  or  pupils  in 
school.  The  method  by  which  one  Boston  teacher  makes 
use  of  the  Auxiliary  Work  has  produced  such  excellent 
results,  and  is  probably  so  generally  feasible,  as  to  deserve 
mention.  As  soon  as  interest  in  the  regular  work  was 
aroused,  a  small  club  was  formed  of  the  most  interested 
pupils,  for  the  purpose  of  fitting  up  a  working  laboratory. 
A  small  one-windowed  room  was  the  only  place  available 


PREFACE   TO   SECOND   EDITION.  XXV 

in  the  schoolhouse.  This  they  supplied  with  a  long,  nar- 
row table  and  a  few  shelves.  They  then  taxed  themselves 
to  purchase  a  pound  of  glass  tubing,  a  Bunsen  burner, 
and  two  files,  and  came  to  me  for  a  "gas-jet-glass-cutter." 
Bottles  and  corks  were  brought  from  home,  and  many 
pieces  of  apparatus  constructed,  which  were  exhibited  to 
the  entire  class  by  their  makers.  As  the  room  was  small, 
and  time  for  work  limited  to  play-hoars  and  Saturday,  the 
teacher  kept  the  "  Laboratory  Club  "  small  by  requiring 
a  certain  standard  of  excellence  in  regular  work  before 
a  pupil  was  eligible  to  membership.  The  teacher  reports 
that  the  plan  has  worked  well,  and  he  believes  some  of 
our  future  Edisons  and  Teslas  are  getting  a  start  in  the 
direction  of  their  bent. 

This  entire  Physical  Science  Course,  Auxiliary  Work 
included,  has  grown  out  of  the  individual  method  of 
teaching ;  and  it  makes  the  application  of  the  method 
possible,  and  even  easy,  in  large  classes,  where  too  fre- 
quently everything  is  machine-work,  every  pupil  being 
required  to  do  the  same  work  at  the  same  time.  The 
method  is  a  discovery  method  in  more  than  one  sense;  not 
only  does  the  pupil  "discover"  the  principles  of  physical 
science,  but  the  teacher  discovers  his  pupils,  and  the 
course  of  work  easily  adapts  itself  to  them  all.  The 
better  pupils  do  more  or  less  of  .the  Auxiliary  Work,  ac- 
cording to  their  interest  and  ability.  This  feature  of 
adaptability  to  different  pupils  shows  itself  more  decidedly 
in  the  quantitative  work  introduced  between  the  almost 
entirely  qualitative  work  of  the  first  seventy-nine  experi- 
ments, and  the  Auxiliary  Work.  Two  of  the  experiments 
in  Specific  Gravity  give  work  severe  enough  for  the  very 


xxvi  PREFACE  TO  SECOND  EDITION. 

ablest  pupils,  while  the  leading  facts  of  all  the  other  ex- 
periments can  be  obtained  by  all. 

THE   QUANTITATIVE   WORK. 

The  twenty-two  Quantitative  Experiments  are  such  as 
the  pupil's  previous  work  has  prepared  him  to  do,  and 
such  as  will  give  him  a  much  more  thorough  understand- 
ing of  the  subjects  he  has  been  studying;  in  fact,  a  fairly 
rounded-out  conception  of  the  physical  properties  of  air 
and  water,  with  the  exception  of  the  effect  of  heat  upon 
them,  which  is  considered  later  in  connection  with,  or  just 
previous  to,  their  chemical  composition.  The  first  nine  of 
these  Quantitative  Experiments  (study  of  Pressure,  Com- 
pressibility, and  Expansibility  of  Air)  require  three  pieces 
of  apparatus  not  put  in  the  pupils'  sets,  chiefly  for  the 
reason  that  one  of  each  is  amply  sufficient  for  a  class. 
These  should  be  experimented  with  by  the  teacher  before 
the  class,  or  placed  in  convenient  positions,  where  each 
pupil  can  use  them  in  turn ;  or,  better  than  either  method 
(in  the  case  of  the  first  one  at  least)  is  a  combination  of 
the  two.  These  pieces  will  cost  about  three  dollars  a  set, 
more  or  less,  according  to  the  size  of  tubes  used  and  con- 
sequent amount  of  mercury.  Explicit  directions  for  mak- 
ing and  setting  them  up  are  given  in  an  appendix. 

METHODS    OF   CONDUCTING   THE   WORK. 

These  will  differ  according  to  circumstances,  the  chief 

"circumstance"  being  the  teacher.     Whatever  method  is 

adopted,  this  fact  should  be  kept  distinctly  in  view,  that 

the  object  is  not  so  much  to  teach  physics  as  to  train  the 


PREFACE   TO   SECOND  EDITION.  XXV11 

pupil  in  the  true  scientific  method.  Teach  him  how  to 
study  nature  so  that,  should  he  be  deprived  of  any  further 
aid  from  the  schools,  he  shall  still  be  prepared  to  see  and 
think  for  himself.  The  discipline  thus  gained  will  be  of 
more  value  to  him  than  would  any  amount  of  facts  taken 
on  trust,  and  the  desire  for  a  higher  education  will  also  be 
thereby  increased. 

First  of  all,  he  must  do  the  experimenting  himself,  not 
only  the  manipulating  of  the  apparatus,  but  the  thinking 
out  of  what  the  experiment  teaches.  Hence  the  work 
must  be  individual ;  for  then  only  can  the  pupil  learn  how 
to  put  questions  to  nature,  and  how  to  read  the  answers. 
Though  a  little  something  may  be  accomplished  by  the 
modern  lecture-table  method,  in  which  the  teacher  does 
the  experimenting,  and  the  pupils  the  thinking  and  writ- 
ing, especially  where  the  conditions  are  most  favorable, 
i.e.,  classes  small,  and  pupils  advanced  and  interested; 
yet  even  then  the  results  are  insignificant  compared  with 
those  obtained  by  the  laboratory  method.  But  in  the  case 
of  large  classes  of  young  pupils  in  various  stages  of  imma- 
turity, the  former  method  not  only  fails  to  accomplish 
much  with  the  best  pupils,  but  for  the  vicious  and  indo- 
lent it  affords  opportunity  for  anything  except  attention 
to  the  lesson  of  the  hour.  For  the  best  "manual-train- 
ing" discipline  somewhat  extensive  experience  and  obser- 
vation have  failed  to  show  the  writer  anything  superior, 
and  but  few  things  comparable,  to  laboratory  physics.  In 
physics  thus  studied  the  pupil  is  fully  engaged,  —  hand, 
head,  and  heart;  for  he  is  always  interested  in  experi- 
menting, hence  he  has  neither  time  nor  disposition  to  stick 
pins  into  his  neighbor.  The  physical  training  in  manipu- 


xxviii  PREFACE  TO  SECOND  EDITION. 

lating  apparatus,  that  is  neither  too  difficult  nor  too  easy  ; 
the  mental  training  in  seeing  what  occurs  and  in  connect- 
ing it  with  its  cause,  if  the  experiment  is  adapted  to  the 
mental  condition  of  the  pupil ;  and  the  moral  training  in 
engaging  the  entire  child  in  the  proper  study  of  those  laws 
under  which  he  "  lives  and  moves  and  has  his  being,"  - 
speak  so  loudly  for  the  laboratory  method,  that  we  do  not 
helieve  any  true  teacher  who  has  ever  tried  it  can  be  per- 
suaded to  adopt  any  other.  The  most  important  thing 
for  the  teacher  to  insist  upon  at  the  beginning,  before  the 
pupil  sees  the  necessity  for  it,  is  that  he  makes  haste 
slowly  ;  that  lie  obtains  the  principal  fact  taught  by  each 
experiment  before  doing  the  next.  If  the  pupil's  actual 
work  is  revealed  to  the  teacher  by  what  he  writes  (which 
was  the  author's  method,  supplemented  by  watching  each 
pupil's  experimenting  so  far  as  time  permitted),  his  notes 
should  be  examined  after  every  laboratory  hour,  and 
marked  according  to  their  deserts.  The  facts  necessary 
to  be  discovered,  and  written  at  each  lesson,  are  few  ;  but 
the  pupil  must  be  held  to  them,  however  they  are  stated, 
or  whatever  else  is  written  in  connection  with  them. 
Here  is  an  excellent  opportunity  to  drill  the  pupil  in  mak- 
ing his  statements  in  clear  and  concise  language.  More 
or  less  time  should  be  given  to  this  work  according  to  the 
pupil's  need. 

The  method  of  conducting  this  course  developed  in  the 
Prince  School  of  Boston  meets  such  hearty  approval  that 
we  have  urgently  requested  its  author — one  of  Boston's 
ablest  grammar  school  principals,  himself  a  teacher  of  phys- 
ics for  many  years  —  to  contribute  an  account  of  it,  for  the 
benefit  of  such  teachers  as  desire  to  study  a  model  method. 


PREFACE   TO   SECOND   EDITION.  XXIX 

LETTER   FROM   PRINCIPAL  YOUNG. 

PROFESSOR  BAILEY: 

Dear  Sir,  —  In  reply  to  your  inquiry  as  to  the  method 
pursued  in  the  use  of  your  "  Course  of  Physics  "  in  the 
Prince  School,  please  find  below  a  statement  in  regard  to 
the  same. 

Believing  in  the  inductive  plan  of  teaching  physics, 
and  in  the  application  of  that  plan  as  presented  in  your 
Course,  I  gladly  availed  myself  of  the  opportunity  to  give 
it  a  trial. 

The  classes  in  which  the  trial  was  made  numbered 
about  forty  pupils  each.  How  to  teach  so  many  pupils  at 
one  and  the  same  time,  secure  their  earnest  attention,  be 
sure  of  their  "  grasping  the  idea  "  in  the  experiment  at 
hand,  and  writing  in  respectable  English  the  conclusions 
reached,  and  all  this  independently  of  one  another,  were 
difficulties  that  must  be  met  and  overcome,  if  the  method 
was  to  find  favor  in  large  public  schools.  After  a  trial  of 
a  year,  and  the  making  of  many  changes  in  the  adaptation 
of  the  method  to  such  conditions,  I  am  free  to  say  that  the 
difficulties  above  mentioned  have  disappeared,  and  the 
success  of  the  Course  seems  to  be  assured. 

Our  final  method  of  using  the  Course  has  been  as 
follows  :  Each  pupil  has  a  desk  of  his  own  with  a  level 
top.  It  contains,  besides  the  box  of  apparatus,  a  pan,  a 
towel,  and  a  tumbler.  There  is  a  pail  for  each  desk, 
which  is  filled  with  water  before  the  lesson  begins. 

During  the  EXPERIMENTAL  LESSON,  each  pupil  works 
independently  and  silently,  guided  only  by  the  printed 
directions  of  the  Course.  In  case  a  piece  of  apparatus  is 


XXX  PREFACE  TO   SECOND  EDITION. 

broken  by  a  pupil,  be  is  allowed  to  raise  his  band  to  attract 
attention.  The  piece  is  at  once  replaced  from  one  of  the 
boxes  near  at  hand,  containing  extra  pieces.1 

After  performing  an  experiment,  the  pupil  is  required 
to  write  his  conclusions  on  paper  provided  for  the  purpose, 
which  must  be  given  to  the  teacher  before  the  next  experi- 
ment is  attempted.  At  the  close  of  the  hour,  the  work  is 
stopped  at  once,  every  unfinished  experiment  or  paper 
being  left  till  the  subject  is  again  resumed.  The  papers, 
when  finished  as  the  experiments  require,  are  numbered 
with  bold  figures  in  the  upper  left-hand  corner. 

They  are  kept  for  the  TALKING  LESSON  given  in  the 
schoolroom,  when  enough  papers  have  accumulated. 
These  talking  lessons  are  conducted  by  the  pupils  them- 
selves, and  are  intended  to  provoke  an  animated  discussion 
of  the  conclusions  written  during  the  experimental  hour. 
Drawings  of  the  apparatus  used  are  made  on  the  black- 
board, questions  asked  and  answered.  In  this  way  the 
facts  taught  through  the  experiments  are  drawn  out,  the 
teacher  meanwhile  guiding  the  line  of  thought,  exciting 
further  inquiry  if  need  be,  but  avoiding  at  all  times  the 
giving  of  direct  information 

At  the  close  of  the  talk  the  papers  are  rewritten  on 
the  back,  and  finally  copied  into  blank  books,  care  l>eing 
taken  to  secure  good  expression  of  the  facts  learned.  The 
books  are  marked,  and  the  results  recorded. 


1  The  amount  of  breakage  varies  not  only  with  pupils  of  the  same 
school,  but  with  schools.  It  is,  however,  much  less  than  is  at  first  expected. 
The  banner  school  in  that  respect,  so  far  as  heard  from,  is  the  Dearborn  of 
Boston,  Principal  Chas.  F.  King.  There  forty-eight  pupils  used  twenty- 
four  sets  of  apparatus  one  year  without  breaking  a  cylinder,  and  so  few 
pieces  that  it  did  not  amount  to  an  average  of  one  cent  per  pupil. 


PREFACE  TO   SECOND   EDITION.  XXXI 

The  pupils  are  thus  led,  (1)  to  experiment  for  them- 
selves, (2)  to  draw  their  own  conclusions,  (3)  to  write  in 
every  case  before  proceeding  farther.  (4)  They  are  given  an 
opportunity  to  interchange  opinions,  (5)  arrive  at  proper 
conclusions  by  taking  time  enough  to  think  over  what 
has  been  done,  and  (6)  are  finally  required  to  write  out 
again  their  inferences  in  good  English  in  blank  books  for 
inspection  and  marking.  Such,  in  brief,  is  the  plan  pur- 
sued in  this  school. 

A  still  further  use  of  the  Course  may  lead  to  other 
changes  in  the  method  as  above  presented,  but  at  present 
the  plan  seems  to  accomplish  all  that  is  desirable ;  viz., 
interest  in  the  subject,  carefulness  in  manipulation,  famil- 
iarity with  principles  taught,  inquiry  into  nature's  ways, 
and  cultivation  in  the  use  of  language. 
Very  truly, 

E.   BENTLEY   YOUNG. 
PRINCE  SCHOOL,  June  20,  1896 


INDUCTIVE 
ELEMENTARY   PHYSICAL  SCIENCE. 


A  LETTER  FROM  THE  AUTHOR 
TO  THE  PUPIL. 

MY  DEAR  YOUNG  FRIEND: 

I  want  to  talk  with  you  a  little  before  we  begin  work 

—  or   play,  I   may  as  well   call    it ;    for  tops,  balls,  and 
marbles  are  by  no  means  the  most  interesting  things  we 
use  in  this    fascinating   scientific    game.     That   it    is    as 
enjoyable  as  play  to  children  of  twelve  to  fourteen  years 
I  know ;  because  the  pupils  in  my  Boston  school,  of  their 
own  accord,  frequently  use  their  recess-hour  for  it,  and 
often  come  before  school  and  on  Saturdays  in  order  to 
do  more  experimenting  than  their  regular  hours  permit. 
That  it  is  the  very  best  way  to  learn  about  the  world  we 
live  in,  all  the  best  teachers  believe ;  because  each  pupil  is 
learning  directly  from  a  better  teacher  than  any  living, 

—  NATURE.      Do   you    remember   how    Longfellow   says 
that   the  great  and  good   Professor  Agassiz  learned  his 
lessons  ? 

"  And  Nature,  the  old  nurse,  took 

The  child  upon  her  knee, 
Saying,  '  Here  is  a  story-book 

Thy  Father  has  written  for  thee.' 


IND  UCTI VE  PH  YSICS. 

And  he  wandered  away  and  away, 
With  Nature,  the  dear  old  nurse, 

Who  sang  to  him  night  and  day 
The  rhymes  of  the  universe. 

And  whenever  the  way  seemed  long, 

Or  his  heart  began  to  fail, 
She  would  sing  a  more  wonderful  song, 

Or  tell  a  more  marvellous  tale." 


Now  I  am  going  to  ask  you  to  adopt  a  motto  that  I 
write  upon  my  blackboard  the  tirst  day  of  every  school 
year;  viz.,  "MATURE  is  our  teacher;  all  the  knowledge 
we  possess  has  come  through  the  patient  study  of  her 
laws."  Then,  whenever  you  are  tempted  to  ask  your 
school-teacher  anything  about  Physical  Science,  I  would 
ask  you  to  stop  and  think,  "Why,  NATIMZK  is  my 
teacher;  I  must  ask  her."  "But,"  say  you,  "  I  don't 
know  how."  That  is  true;  and  that  is  the  reason  I  have 
arranged  this  series  of  questions  (experiments)  for  \<>n, 
in  order  to  tell  you  how  to  ask  them.  If  you  do  as  I 
direct,  you  will  not  only  be  greatly  interested  and  in- 
structed by  the  answers  you  obtain,  but,  what  is  /<//• 
better,  you  will  learn  how  to  put  questions  yourself. 
Then  you  will  continue  through  life  studying  Nature 
wherever  you  are.  You  will  become  an  original  investi- 
gator, and  possibly  a  discoverer  and  an  inventor.  All 
the  great  discoveries  and  inventions  were  made  by  men 
who  first  learned  how  to  put  their  questions  to  this 
GREAT  TEACHER,  and  interpret  the  answers. 

Now  let  me  tell  you  how  to  study  this  course,  that  it 
may  afford  you  the  most  pleasure  and  profit.  First.  Per- 
form every  experiment  in  order.  Do  not  omit  one  because 


LETTER    TO   PUPIL.  3 

it  looks  so  simple  that  you  think  you  know  all  about.it. 
None  of  us  knows  all  about  anything.  Secoml.  Always 
experiment  carefully  and  thoughtfully.  If  you  work  hur- 
riedly, carelessly,  or  without  watching  to  see  everything 
that  happens,  and  without  thinking  out  for  yourself  the 
reason  for  it,  it  will  do  you  little  or  no  good.  And,  of 
course,  if  you  must  not  be  told  «•////  anything  happens,  you 
should  not  tell  your  classmate,  and  so  deprive  him  of  the 
pleasure  and  benefit  of  discovering  for  himself.  .  Possibly 
you  may  perform  an  experiment  and  not  see  the  why  of 
it  at  first ;  if  so,  give  it  a  little  careful  thought,  remember 
the  what,  and  perhaps  the  very  next  experiment  will  show 
you  the  wliy.  If,  however,  two  or  three  experiments  do 
riot  help  you  out  of  your  difficulty,  probably  you  have 
not  done  the  previous  work  well  enough,  and  had  better 
review  it.  TliinL  When  you  see  what  an  experiment 
teaches,  you  must  tell  it  in  your  own  language  on  paper. 
It  will  not  do  you  half  the  good  to  give  it  in  spoken 
words  ;  you  must  write  it.  Number  each  inference,  —  that 
is,  what  the  experiment  teaches  you,  —  and  write  it  at  the 
time  you  do  the  experiment.  Your  thought  being  chiefly 
on  the  experiment  and  what  it  teaches,  you  will  not  ex- 
press it  in  the  very  best  language  now  without  mistakes ; 
therefore  you  should  re-write  it.  Let  me  tell  you  our 
method,  for  it  is  the  best  we  have  yet  discovered.  After 
experimental  work  our  pupils  have  an  hour  for  writing 
the  lesson ;  this  they  do  on  ruled  note-books  in  the  form 
of  a  chapter  on  science.  Each  lesson  is  dated ;  it  begins 
at  the  top  of  a  page,  and  is  written  only  on  the  right-  or 
else  the  left-hand  side  (always  the  same),  the  other  being 
left  for  corrections.  The  experiment,  observation,  and 


4  INDUCTIVE  PHYSICS. 

inference  are  given;   the  first  is  usually  illustrated  with 
a  small  drawing.1 

The  pupils  preserve  their  books,  and  at  the  end  of  the 
year  it  is  a  good  plan  to  have  them  bound.  Pupils  prize 
these  books  more  highly  than  any  others  in  their  libraries, 
for  they  are  entirely  of  their  own  making.  What  I  ask 
you  to  do  is  one  thing  that  did  much  towards  the  disci- 
pline of  George  Washington,  for  we  are  told  upon  good 
authority,  that  "he  made  his  own  schoolbooks." 

Hoping  that  you  will  do  likewise,  and  meet  with  success 
through  life,  I  am, 

Your  true  friend  and  fellow-student, 

V.  II.  BAILEY. 
6  MARLBORO  STREET,  BOSTON,  MASS. 

1  SUGGESTIONS  FOR  CORRECTING  BOOKS. —  After  school  I  look  over  the 
work,  and  with  red  pencil  mark  the  mistakes  with  such  signs  as  (jr.  for 
grammatical  error;  sp.  under  word  for  misspelled;  a  wrong  or  unsuitable 
word  or  expression  is  marked  underneath  u.w.  or  u.ex;  a  statement  Unit 
is  wrong,  or  that  had  better  be  reconsidered  and  re-written,  is  enclosed  in 
parentheses  and  marked  with  an  interrogation  point,  thus  (— )?.  The  next 
day  the  pupils  correct  their  mistakes,  changing  nothing  on  the  written  pn^e. 
but  making  the  corrections  directly  opposite.  Then  the  next  time  the  books 
are  inspected,  if  all  corrections  are  satisfactorily  made,  an  A  (accepted)  is 
placed  at  the  top  of  the  page. 


STUDY   OF   APPARATUS. 


"100  IN  1  PHYSICAL  SCIENCE  APPARATUS." 

IT  is  very  essential  that  you  should  know  what  articles 
are  contained  in  your  set  of  apparatus,  and  what  each 
article  is  called  throughout  the  book.  Begin  with  No.  1 ; 
read  its  name,  find  its  picture,  and  then  the  article  itself 
in  3'our  box.  Go  through  the  entire  list  the  same  way. 
Nos.  1,  2,  and  3  are  shown  in  Fig.  1,  but  are  not  there 
numbered.  A  few  common  and  easily  recognized  ar- 
ticles —  Nos.  34  to  47  —  are  not  illustrated.  A  few 
pieces  of  which  there  are  several  of  a  kind,  are  shown  as 
they  are  connected  for  use.  The  small  rubber  balloon  you 
are  cautioned  not  to  distend  by  blowing  into  it.  These 
balloons  are  not  always  of  the  best  quality,  though  we  try 
to  have  them  so.  They  come  from  Germany,  and  some- 
times an  entire  shipment  will  be  poor.  However,  the  poor- 
est are  all  right  for  the  experiment  for  which  they  are 
intended ;  as  they  are  not  to  be  blown  up,  but  only  filled 
with  in-rushing  air.  Another  piece  that  is  liable  to  be 
spoiled  by  abuse  is  the  4-inch  square  of  sheet  rubber.  Use 
it  only  as  directed.  Do  not  try  to  see  if  it  will  stretch 
enough  to  cover  your  desk.  It  might  not.  Should  you 
tear  it,  however,  any  dentist  could  supply  you  with  a 
thinner  sheet  that  will  answer  very  well. 

Those  who  desire  to  make  their  own  apparatus  will 
find  directions  in  the  Preface  and  in  the  "  Auxiliary 


6  INDUCTIVE  PHYSICS. 

Work  "  in  the  back  part  of  the  book.  No.  1  of  the  list 
is  called  the  "  100  in  1  Physical  Science  Apparatus,"  be- 
cause about  a  hundred  experiments  are  performed  with  it 
and  its  various  attachments.  The  experiments  of  winch 


it  is  capable  are  not  all  given  in  this  book,  for  the  express 
reason  that  it  is  thought  best  to  allow  you  the  opportunity 
of  inventing  some.  Throughout  the  book  this  piece  is 
called  the  "  Apparatus."  Wherever  the  same  word  begins 
with  a  small  "a"  it  does  not  refer  to  this  particular  pirr«\ 
as  in  the  first  paragraph  on  page  5. 


STUDY   OF  APPARATUS. 


18 


Fig.  3. 


19 


APPARATUS   ILLUSTRATED. 


No.  1.  Apparatus. 

2.  Rubber  Stopper. 

3.  3  feet  of  Rubber  Tubing. 

4.  Tin  Can  and  Cover. 

5.  12-inch  Tin  Tube. 

0.  Bottle  and  Attachment. 

7.  Wide-mouth  Bottle. 

S.  Bottle  Imp. 

9.  Vial  of  Mercury. 

10.  Pressure  Gage  with  rubber 

connector. 

11.  Pressure  Gage  Attachment 

with  rubber  connector. 


No.  12.    3    Short    Jot-tubes ;    one 


13. 
14. 
15. 
'16. 

17. 

18. 
19. 
20. 

with    "packing" 
"cap." 
4  pieces  of  Packing. 
4  Jet-tube  Caps. 
2  Rubber  Valves. 
2  Connecting  Tubes  ; 
with    "  packing  " 
"  valve." 
Heavy  Rubber  Tube. 
6-inch  Tube. 
Piston  or  Plunger. 
Piston  Tube. 

and 

one 
and 

A 


INDUCTIVE  PHYSICS. 

A  A  /\ 


25 


27 


22 


Fig.  4. 


No.  21.   Piston  Tube  Attachment; 

with  "  packing." 

22.  8-inch  Jet-tube. 

23.  6-inch  Curved  Jet-tube. 

24.  6-inch    Elbow    Jet-tube  ; 

with  "cap." 

25.  4-inch  Elbow  Jet-tube. 

26.  4-inch  Straight  Jet-tube. 

27.  4-inch  Curved  Jet-tube. 


No.  28.   Elbow  Tube. 

29.    2   Elbow   Jet-tubes  ;    one 

"  capped." 

00.    Equal-arm  U-tube. 
81.   Unequal-arm     U-tube; 

with  "packing." 

32.  2  Fine  Tubes. 

33.  Rubber   Balloon    and    6- 

inch  Tube. 


STUDY  OF  APPARATUS. 


APPARATUS   NOT   ILLUSTRATED. 


No.  34.  4  Glass  Marbles. 

35.  Wooden  Ball. 

36.  4  "  2  Buck  Shot." 

37.  4  "  Single  F."  Shot. 

38.  Sheet  Rubber,  4  in.  sq. 

39.  Square  of  Cheese  Cloth. 

40.  2  in.  sq.  Wire  Cloth. 

41.  2  in.  sq.  Glass. 


No.  42.  2  in.  sq.  Tin. 

43.  2  in.  sq.  Card. 

44.  2  in.  sq.  Wood. 

45.  Shot  Punch. 

46.  1-inch  Rattan. 

47.  Cork,   Stick,   String,  and 

Rubber  Bands. 


Fig.  5. 


ADDITIONAL   APPARATUS  FOR   QUANTITATIVE  WORK. 


TO  PUPILS'  SETS. 

No.  48.    Scales,  Block,  Rider,  and 

Apparatus  Hook. 
49.    25  Grain  Weights. 


CLASS    PIECES. 

No.  50.    Barometer  with  Mercury. 

51.  Balancing  Liquids,  Tubes, 

and  Mercury. 

52.  "Boyles'  Law  "  Piece  and 

Mercury. 


FIRST   EXPERIMENTAL  WORK. 


DIRECTIONS  FOR  ADJUSTING  THE  "100  IN  1  PHYSICAL 
SCIENCE  APPARATUS." 

IT  is  useless  to  attempt  to  perform  the  experiments  of 
this  course  without  first  learning  how  to  manipulate  the 
apparatus.  You  should  follow  these  directions  carefully, 
and  practise  them  until  the  pieces  of  the  apparatus  can  be 
put  together  and  taken  apart  properly  and  readily ;  then 
the  experimenting  will  become  easy,  pleasurable,  and  prof- 
itable. 

First  remember  that  in  every  experiment,  unless  other- 
wise directed,  the  holes  in  the  "  100  in  1  Apparatus  "  (see 
illustration  to  EXP.  2),  or  in  the  bottle  used  instead  (see 
illustration  to  EXP.  9);  also  in  the  rubber  stopper,  should 
be  plugged.  To  plug  the  hole  in  the  bottom  of  the 
Apparatus  or  bottle,  stand  it  bottom  upwards ;  wet  thor- 
oughly a  J-inch  piece  of  rubber  tubing  or  "packing; 
insert  just  barely  into  one  end  a  shot  (the  smaller  of  the 
sizes  furnished  with  the  set)  large  enough  to  slightly 
stretch  the  "packing  ;  "  thrust  the  free  end  into  the  hole 
until  the  shotrloaded  end  is  even  with  the  outer  surface  ; 
then  with  the  thumb  push  the  shot  well  into  the  packing. 
If  the  packing  is  not  inserted  far  enough  to  allow  the 
Apparatus  to  stand  steadily,  it  is  not  well  done;  and,  ;is 
it  is  scarcely  possible  to  push  the  rubber  in  farther  alter 
10 


FIRST  EXPERIMENTAL    WORK.  11 

the  shot  has  been  crowded  in,  both  shot  and  packing 
should  be  removed,  and  another  trial  made.  In  fact,  trials 
should  be  made  until  this  method  of  plugging  can  be  easily 
and  properly  done  every  time.  To  remove  the  shot  and 
packing,  first  stand  the  Apparatus  inverted  in  the  pan, 
then  push  them  through  with  the  nail.  The  holes  in  the 
side  of  the  Apparatus  may  be  plugged,  and  the  plugs 
removed  in  the  same  way,  except  with  the  Apparatus 
lying  upon  its  side.  As  it  does  not  matter  if  the  rubber 
packing  projects  from  the  side  holes,  the  shot  may  be 
pushed  farther  into  the  packing  before  it  is  inserted  than 
when  used  for  the  bottom  hole. 

The  side  holes  may  be  plugged  with  the  small  glass 
jet-tubes  (see  Exi>.  2)  as  follows :  Wet  a  "  cap  "  or  £ -inch 
piece  of  rubber  tubing  with  a  shot  in  the  end,  and  push  it 
over  the  small  end  of  the  jet-tube  ;  put  a  piece  of  packing 
just  barely  over  the  other  end;  then  seizing  that  part  of 
the  ] lacking  stretched  by  the  glass,  push  it  into  the  hole, 
and  then  with  a  twisting  motion  thrust  the  tube  in  until 
it  is  held  firmly. 

To  connect  any  glass  tul)e  with  the  Apparatus,  put  a 
piece  of  wet  packing  over  the  end  of  the  tube ;  grasp  it  at 
the  place  where  the  rubber  is  distended  by  the  glass ;  in- 
sert the  packing  into  the  hole,  and  then  push  in  the  tul>e 
with  a  twisting  motion  until  it  is  held  firmly.  If  the  rub- 
ber packing  is  pushed  clear  through  the  hole,  —  which  may 
happen  if  the  glass  tube  is  the  least  particle  smaller  than 
it  should  be,  — thrust  the  end  of  the  glass  tube  a  little 
farther  into  the  packing,  wipe  the  outside  of  the  latter 
dry.  and  try  again. 
.  To  remove  a  jet-tube  or  other  glass  tube  from  a  hole, 


12  INDUCTIVE  PHYSICS. 

seize  it  firmly  near  the  packing,  and  draw  it  out  with  a 
twisting  movement. 

Never  leave  glass  tubes  connected  with  the  Apparatus. 
Never  leave  shot  inside  the  packing;  as  it  is  hard  to 
remove  when  dry,  though  very  easy  when  wet.  Never 
remove  the  shot  from  the  caps  or  valves.  Never  leave  wet 
packing,  caps,  or  other  rubl>er  on  a  glass  tube  ;  after  dry- 
ing they  are  apt  to  stick  to  each  other  so  firmly  that  they 
are  not  easily  separated.  The  glass  tubes  are  not  very 
easily  broken,  and  with  decent  care  there  is  no  need  of 
ever  breaking  one. 

If  the  long  piece  of  rubber  tubing  has  been  used  with 
water,  blow  the  latter  out  before  putting  the  tubing 
away.  The  sheet  rubber  should  be  dried  with  a  cloth. 

Do  not  attempt  to  perform  any  experiment  in  a  care- 
less, slipshod  manner.  If  you  are  not  careful  and  orderly, 
you  cannot  hope  for  success  in  any  pursuit.  Begin  now 
by  being  careful  of  your  apparatus.  Try  to  be  exact; 
always  do  your  work  neatly ;  and  always  put  your  appa- 
ratus away  in  good  order  when  you  have  finished  your 
work. 


WATER   EXPERIMENTS. 


Experiment  1.    Fill    the    Apparatus,    or    bottle    used 
instead,  to  the  brim  with  water,  and  insert  a  finger. 
OBSKRVATION.    What  happens? 
INFERENCE.    AVliy  ? 


Exp.  2. 


Exp.  2.  Fill  the  Apparatus  with  water ;  crowd  a  large 
shot  into  each  hole  in  the  smaller  end  of  the  rubber 
stopper,  then  try  to  insert  it  into  the  Apparatus. 

OBSERVATION  AND  INFERENCE. 

Bxp.  3.  Remove  the  shot  from  the  stopper,  then 
insert  it  into  the  Apparatus. 

OBSERVATION. 

13 


14  INDUCTIVE  PHYSICS. 

INFERENCES.  1.  Why  can  you  easily  insert  it  now  ?  2. 
What  do  these  three  experiments  teach  you  about  water  that 
is  also  true  of  everything  you  can  see  or  handle  ? 

Exp.  4.  Weigh  the  Apparatus  ;  fill  with  water,  and 
weigh  again.  (The  weight  may  be  estimated  if  scales  are 
not  accessible.) 

OBSERVATION. 

INFERENCES.  1.  What  does  this  experiment  teach  about 
water  ?  2.  WTould  it  have  weight  if  there  were  no  force  pull- 
ing or  pushing  it  towards  the  earth  ?  3.  Is  it  the  same  force 
that  causes  a  ball  thrown  upward  to  fall  back  to  the  earth  ? 
4.  Do  you  know  its  name  ?  (It  has  a  name,  but  we  do  not 
know  much  about  it.)  5.  Towards  what  point  in  the  earth 
does  this  force  pull  everything  on  the  earth  ?  6.  Draw  a 
circle  to  represent  the  earth,  and  illustrate  the  direction  in 
which  objects  fall  on  different  sides  of  the  earth,  .showing 
where  they  would  meet  if  they  could  fall  through  the  earth 
as  easily  as  through  air. 


Exp.  5. 


Exp.  5.  1.  Push  the  marble  equally  from  opposite 
directions.  2.  Push  harder  with  one  finger  than  with 
the  other.  3.  With  thumb  and  finger  of  one  hand  press 
equally  upon  opposite  points,  and,  with  thumb  and  linger 
of  the  other  hand,  press  equally  upon  opposite  points  half 
way  between.  4.  Press  equally  with  both  thumbs  and 


T»  'A  TEE   EX  PERI  MEN  TS. 


15 


one   finger,  but  harder  with  the   other  finger.     5.    Seize 
your  pencil  with  both  hands,  and  pull  equally  with  each. 

6.  Pull    harder   with    one    hand    than    with    the    other. 

7.  Pull  with  one  hand  only. 

INKEKENCES.  1.  When  and  in  what  direction  do  things 
move  ?  2.  When  do  they  remain  at  rest  ? 

Exp.  6.  Hold  a  marble  an  inch  or  two  above  the  pan, 
and  let  go  of  it.  Place  it  at  one  end  of  the  pan,  then 
raise  that  end  a  little. 

INKEKENCES.  1.  How  many  forces  were  acting  upon  it 
while  you  held  it  ?  2.  Why  did  it  drop  ?  3.  Was  it  pulled 
or  pushed  towards  the  earth  ?  4.  After  it  came  to  rest,  was 
it  still  pulled  or  pushed,  and  if  so,  why  did  it  not  move  ? 
5.  Why  did  it 'move  when  the  pan  was  tilted  ? 

Exp.  7.    Cap  the  small  ends  of  the  jet-tubes,  and  in- 
sert them  in  the  side  holes  of 
the   Apparatus.      Fill   it   with 
water,    and    remove    the    cap 
from  the  lower  jet-tube. 

INFERENCE.  In  what  other 
direction  than-  downwards  does 
water  press  ? 

Exp.  8.  Upon  three  mar- 
bles, touching  each  other  on  a 
smooth  surface,  place  a  fourth. 

INFERENCES.  1.  What  causes  the  three  to  roll  apart? 
2.  Now  explain  why  water  presses  sideivays.  3.  Do  other 
liquids  press  sideways?  4.  Do  solids  press  sideways?  5.  If 
you  should  hold  your  hand  beside  the  wall  of  a  brick  house, 
would  the  bricks  press  sideways  against  your  hand  ?  6.  If  you 


Exp.  8. 


INDUCTIVE  PHYSICS. 


had  a  barrel  full  of  marbles, 
you  bored  a  large  hole 
near  the  bottom,  what 
would  happen  ?  If  fine, 
dry  sand  is  convenient, 
with  a  finger  over  the 
lower  hole,  fill  your  Ap- 
paratus, then  remove  the 
finger,  and  see  how  strik- 
ingly the  stream  of  sand 
resembles  one  of  water. 
8.  When  do  solid  sub- 
stances act  very  much 
like  liquids?  9.  What 
is  the  difference  between  E 


fine  shot,  or  of  fine,  dry  sand,  and 


Exp.  10. 


bow  jet-tube  as  illustrated,   and 


Exp.  9. 

solid  and  a  liquid  ? 

Exp.  9.  Cap  the 
jet-tubes,  fill  the  Ap- 
paratus with  water, 
hold  it  above  the  pan, 
and  uncap  both  jet- 
tul)es. 

INFKKKNCK.  What 
more  does  this  experi- 
ment teach  you  about 
side  pressure  than  did 
EXP.  7  ? 

Exp.  1O.  Insert 
capped  jet-tubes  i  n 
three  holes  of  the  long 
tin  tube,  plug  the  other 
hole  with  a  capped  el- 
fill  the  tin  tube  with 


WA  TER   EXPEUIME\  7X 


17 


water.      Uncap  the  three  straight  jet-tubes.     Study  also 
Aux.  1. 

INFERENCE.  What  more  do  these  experiments  teach  you 
about  side  pressure  than  did  EXP.  9  ? 

Bxp.  11.  Insert  into  the  bottom  hole  of  the  Apparatus 
a  short  jet-tube  with  small  opening  inside,  and  press  the 
Apparatus  well  down  into  a  jar  or  pail  of  water  until  a 
fountain  is  produced. 


Exp.   11. 


Exp.   12. 


INFERENCE.    In  which  direction  does  the  water  press  ? 

Exp.  12.  With  bottom  hole  open,  place  a  card  over 
the  mouth  of  the  Apparatus,  invert,  and  press  it  down  into 
the  water.  Repeat,  using  a  disk  of  metal  (iron,  zinc,  or 
lead),  and  also  one  of  glass.  The  metal  and  glass  disks 
must  be  held  against  the  Apparatus  till  immersed  an  inch 
or  two.  (If,  instead  of  a  tin  pail,  you  are  using  a  jar  not 
large  enough  to  admit  the  hand,  keep  the  disk  in  place  by 
means  of  a  string  or  wire  passed  under  it,  the  ends  being 
held  in  the  hand.)  As  the  water  leaks  in  until  the  disk 
finally  falls,  compare  its  height  inside  and  outside  of  the 
Apparatus. 


18  INDUCTIVE  PHTSICS. 

INFERENCES.  1.  What  forces  here  act  in  opposite  direc- 
tions ?  2.  Which  force  is  the  greater  until  the  disk  falls  ? 
3.  Why  does  not  the  disk  move  in  obedience  to  the  greater 
force?  4.  Which  force  is  being  constantly  increased  until 
it  overcomes  the  greater,  and  how  is  it  increased?  5.  Why 
must  a  heavy  disk  be  immersed  deeper  than  a  light  one  in 
order  to  be  held  up  at  all  ?  6.  Is  there  any  resemblance 
between  the  law  for  water  pressure  upward  and  sideways? 

7.  What  do  you  think  causes  upward  pressure  in   water  ? 

8.  Do  you  think  that  upward  pressure  is  the  same,  or  that 
it  exists  at  all  in  other  liquids  ? 

Exp.  13.  Thoroughly  wet  the  rubber  stopper,  then 
insert  the  three  4-inch  jet-tubes  as  illustrated,  with  the 
lower  openings  all  at  the  same  level. 
Immerse  the  lower  ends  of  the  tubes 
in  water,  and  notice  in  which  direc- 
tion the  water  must  press  in  order  to 
enter  each;  observe  the  height  to 

_  _  which  water  rises  in  each.  Be  sure 

that  the  upper  jet  ends  of  the  tube 
are  not  stopped  with  water. 

INFERENCES.    1.    Compare  pressure 
in   all    directions   at    the    same  depth. 
Exp.  13.  %•    Compare    with    Ex  PS.    9,    1O,    ;ind 

Aux.  1,  and  tell  what  you  can  without 

more  experiments  about  upward  pressure  at  different,  depths. 
3.  How  does  upward  pressure  two  inches  below  the  sui  tact- 
compare  with  upward  pressure  one  inch  below  ? 

NOTE.  —  The  right  arm  of  the  pressure-gage  in  the  "  100  in  1  "  set 
of  apparatus  js  considerably  shorter  than  is  shown  in  the  cut  ;  it  must 
be  lengthened  by  one  of  the  6-inch  pieces  of  straight  tubing  and  a 
rubber  connector. 


WA  TEE   EXP  E  RIM  EN  TS. 


19 


Exp.  14.    Fill    the    bend    of    the    pressure-gage    two- 
thirds  full  of  water,  and  slowly  in- 
sert the  lower  end  several  inches 
into    the    Apparatus    or    dish    of 
water. 

INFERENCE.  Does  this  experi- 
ment prove  that  your  second  infer- 
ence in  Exi>.  13  is  correct  ? 

Exp.  15.  With  the  attachment 
on  the  lower  end  of  the  pressure- 
gage,  repeat  above  experiment; 
also  attach  the  elbow-tube  and  re- 
peat. 

INFERENCE.  Do  these  results  con- 
firm your  previous  inferences  about 
pressure  sideways  and  downward  ? 

Exp.  16.  (See  Aux.  2.)  Insert  pressure-gage  to  the 
same  depth  in  water  contained  in  dishes  of  various  sizes 
and  shapes. 


Exps.  14  and  15. 


INFERENCES.  1.  Upon  what  one  thing  only  does  the 
upward  water  pressure  against  the  air  in  the  gage  depend  ? 
-.  Would  it  be  any  greater  at  the  same  depth  in  a  lake  or 
pond?  3.  Upon  what  tiro  tilings  does  the  downward  pres- 
sure upon  the  bottom  of  a  dish  full  of  water  depend  ?  4.  Is 


20 


INDUCTIVE  PHYSICS. 


the  pressure  on  the  bottom  of  dish  2,  below,  greater  than  that 
on  dish  1  ?  5.  How  do  you  know  ?  G.  Is  the  pressure  on 
the  bottom  of  either  dish  just  equal  to  the  weight  of  the 
water  it  contains  ?  7.  In  the  other,  is  it  greater  or  less  than 
the  weight  of  the  water?  8.  With  dish  3,  how  does  the 
pressure  on  the  bottom  compare  with  that  of  the  others? 
9.  Why  ?  10.  How  does  the  pressure  compare  with  the 
weight  of  Hie  water?  If  the  inside  of  dish  1  is  just  1  foot 


Fig.  6. 


square  on  each  side,  it  will  hold  02.5  Ibs.  of  water.    11.  What 
is  the  pressure  against  one  side  of  the  dish,  if  full  of  water  ? 

12.  What  is  the  total  pressure  against  the  sides  and  bottom  '.' 

13.  What  is  the  total  water  pressure  against  sides  and  bottom 
of  a  dish  twice  as  long,  but  the  same  width,  and  holding  the 
same  amount  of  water  ?     Make  a  drawing  of  the  dish,  or  a 
diagram  of  the  bottom,  one  side,  and  one  end.     14.    A  dish  is 
twice  as  long  and  twice  as  wide  as  No.  1,  but  holds  the  same 
amount  of  water.    What  is  the  total  water  pressure  on  bottom 
and  sides?     Draw  or  diagram  the  dish.     15.    What  is  the 
depth  of  each  dish  ?     16.    As  a  general  fact,  is  the  total  pres- 
sure of  a  certain  amount  of  water  more  if  held  in  a  deep  dish 
with  small  bottom,  or  in  a  shallow  dish  with  large  bottom  ? 
17.    A  deep  dish  and  a  shallow  dish,  both  with  perpendicular 
sides,  hold  each  the  same  amount  of  water ;  how  does  the 
pressure  on  their  bottoms  compare  ? 


WATER   EXPERIMENTS. 


21 


That  which  belongs  to  you  is  called  your  property. 
Call  anything  that  belongs  to  water  its  property,  and  tell 
briefly  what  properties  of  water  you  have  thus  far  dis- 
covered ;  also  state  the  two  leading  facts  about  water 
pressure.  By  use  of  these  facts  explain  the  following 
experiments. 

Bxp.  17.  Fill  the  Apparatus  with  water,  and  observe 
the  tube. 

INFERENCE.    Explain  why  liquids  "  seek  their  own  level." 


u 

— 

Exp.   17. 


Exp    18. 


Exp.  18.  Connect  the  Apparatus  and  tin  can  by  means 
of  packing,  connecting-tubes,  and  long  rubber  tube ;  pour 
water  into  one,  and  watch  both.  Kaise  and  lower  one, 
watching  effects.  Place  them  close  together,  near  the 
edge  of  the  table  or  desk,  with  the  rubber  tube  hanging- 
over,  and  fill  one  with  water.  Vary  their  relative  posi- 
tions and  the  position  of  the  tube  as  much  as  possible. 
Note  and  explain  fully  whatever  takes  place. 

OBSERVATION  AND  INFERENCK. 

NOTT?,.  —  Did  you  ever  see  a  carpenter's  spirk-leveJ  ?  If  so,  com- 
pare it  with  the  water-level  (Aux.  3)  and  with  EXP.  18:  if  not,  find 
one,  and  study  it  as  soon  as  convenient. 


22 


INDUCTIVE  PHYSICS. 


Bxp.  19.  With  the  Apparatus  full  of  water,  raise  the 
jet-tube  till  it  contains-no  water,  then  lo.wer  it  till  a  foun- 
tain is  formed. 


Exp    19. 

INFERENCES.  1.  Explain  how  water  from  reservoirs  is 
supplied  to  towns  and  cities.  2.  Why  are  reservoirs  built 
on  hills  ?  3.  Why  do  cities  located  in  level  countries  build 
standpipes  or  water-towers?  4.  On  which  floor  of  tall  build- 


Fig.  7. 

ings  thus  supplied  with  water  does  it  escape  most  rapidly,  and 
why?  Write  about  this  subject  as  fully  as  you  can,  ainl  sec 
if  you  can  apply  the  same  principle  to  explain  country  water- 
supply  by  wells  or  springs.  '(See  Aux.  4.)  Explain  water- 
supply  as  shown  in  Fig.  7. 


WATER   EXPERIMENTS. 


E. — EXPS.  20  and  21  require  a  high  point  of  suspension. 
Where  it  is  not  convenient  to  arrange  a  hook  directly  above  each  pupil's 
desk  or  table,  a  few  hooks  and  strings  should  be  provided  where  pupils 
can  go  in  turn  or  in  very  small  groups,  to  experiment.  Usually  hooks 
may  be  inserted  into  the  top  of  window-casings,  and  strings  attached, 
reaching  to  within  about  one  foot  of  the  window-sill.  (See  Auxs.  4  and 
5.)  As  the  Apparatus  is  not  tall  enough  to  make  these  experiments 
very  striking,  the  12-inch  tin  tube  is  provided. 


i 


Exp.   20. 


Exp.  2O.  Suspend  the  tin  tube  as  illustrated  by  us 
long  a  string  as  possible  just  above  a  table  or  a  window- 
sill.  Steadying  it  with  one  hand,  carefully  remove  both 
cap  and  tube  together  from  one  lower  hole  with  the  other 
hand,  and  let  go  of  the  tube  at  the  same  time. 


INDUCTIVE  PHYSICS. 


INFERENCE.  Why  does  the  tube  swing  away  from  the  jet 
of  water  ? 

Bxp.  21.  With  the  tube  still  hanging,  insert  elbow  jet- 
tubes  in  both  of  the  lowest  holes  so  as  to  point  in  opposite 
directions,  and  fill  with  water.  Experiment  in  a  variety 
of  ways,  thus :  with  both  jet-tubes  horizontal  and  the  tin 


A 


Exp    21. 


Exp.  22. 


tube  hanging  within  a  pail  to  catch  the  water;  with  one 
tube  horizontal,  the  other  at  any  angle;  with  tulx's  at 
different  angles  imitating  a  lawn  fountain;  with  both 
tubes  horizontal  and  under  water;  etc. 

INFERENCE.    At  exactly  what  point  or  points  is  the  pres- 
sure applied  that  causes  the  rotation  ? 

Exp.  22.    Fill  the   Apparatus  and  rubber  tube   with 
water.     To  fill  the  latter,  let  it  lie  on  the  table,  and  pour 


WATER  EXPEIUMENTS. 


or. 


water  into  the  Apparatus ;  then,  when  the  water  begins 
to  run  out  of  the  tube,  plug  the  end  with  capped  jet-tube. 
When  the  Apparatus  is  as  full  as  possible,  tie  the  piece  of 
sheet  rubber  over  the  mouth,  and  place  a  weight  of  about 
a  pound  upon  it.  Insert  a  funnel  in  place  of  the  plug. 
Pour  water  into  the  funnel  (see  note  to  Aux.  6),  and 
raise  it  to  the  length  of  the  tube. 

INFERENCE.  Explain 
why  so  little  water  raises 
so  heavy  a  weight.  See 
Aux.  6. 

Bxp.  23.  Alter- 
nately lower  and  raise 
the  stopper,  and  see  if 
you  can  tell  with  your 
eyes  shut  when  it  en- 
ters or  leaves  the 
water.  Try  also  the 
wooden  ball. 

INFERENCE.  Explain 
as  fully  and  carefully  as 
you  can  why  the   stop- 
per when  under  water  seems  to  weigh  less,  and  why  the  ball 
floats. 

NOTE. — Later  in  our  course  we  shall  have  several  interesting 
experiments  similar  to  this  ;  hut  you  ought  to  see  clearly  now  what 
causes  this  buoyant  force  of  water,  as  it  is  called.  Is  a  fish  or  a  stone 
as  heavy  in  water  as  it  is  out  ?  Explain. 

Exp.  24.  Push  the  Apparatus  along  the  table  with 
your  pencil. 

INFERENCE.  In  what  one  direction  only  is  the  pressure 
which  your  hand  applies  to  the  pencil  transmitted  to  the 
Apparatus  ? 


Exp.  23. 


INDUCTIVE  PHYSICS. 


Exp.  25. 


Exp.  25.  Place  capped  jet-tubes  in  the  side  holes  of 
the  Apparatus,  and  plug  the  bottom  hole  with  shot  and 
packing.  Completely  fill  it  with  water,  and  fasten  the 

sheet  rubl>er  over  the 
month  with  a  siring. 
Invert,  push  the  shot 
inside  with  the  shut- 
punch,  and  put  a 
capped  jet-tube  in  its 
place.  Lay  it  down, 
-  as  represented,  with 
jet-tubes  all  the  same 
distance  above  the  pan 
or  table,  remove  the  jet-caps,  and  tap  gently  on  the  rub- 
ber with  your  fingers. 

INFERENCE.  Compare  with  EXP.  24,  and  explain  the  dif- 
ference between  solids  and  liquids  in  transmitting  applied 
pressure. 

Exp.  26.    With  the  Apparatus  full 
of  water,  step  to  an  open   window,  or 
any  convenient  place,  and  blow  through 
the  rubber  tube.     Determine  by  experi- 
ment whether   you   have   to   blow  any 
harder  to  raise  several  jets  of  Water  to 
a  given  height  than  to 
raise  one.     See  Aux.  7. 
INFERENCE. 
NOTE.  —  When     condi- 
tions  are  favorable,  a  very 
pretty  variation  of  EXP.  26 

may  be  made  by  combining  it  with  Aux.  4,  using  varying   numbers 
of  jet-tubes,  and  varying  the  height  of  the  Apparatus. 


WATER   EXPERIMENTS. 


Exp.  27.    Fill  the  Apparatus  with  water,  insert  the 
stopper  tightly  with  one  hole  open,  and  measure  the  part 
of    the    stopper    above    the    glass. 
Carefully    push    the    piston-rod    or 
"plunger"  through   the   open  hole 
to  the   bottom,  and  again  measure. 
The  measurements  should  be  made 
with  care. 

INFERENCE. 

Exp.  28.  Arrange  the  Appara- 
tus the  same  as  in  EXP.  27,  but 
insert  a  short  jet-tube  in  one  hole 
of  the  stopper.  Hold  the  palm  of 
one  hand  about  two  feet  above; 
seize  the  piston-rod  at  a  point  where  Exp.  27. 

the   plunger  end,  when  pushed  in, 

will  not  quite  reach  the  bottom  of  the  Apparatus ;   then 
push  it  down  suddenly. 

INFERENCE. 

NOTE.  —  In  doing  EXP.  29,  insert  the  tube  into  the  Apparatus 
farther  than  is  shown  in  the  cut,  and  grasp  hoth  together  with  one 
hand  while  working  the  piston  with  the  other. 

By  "  size  "  of  a  tube  is  meant  the  size,  not  the  length, 
of  the  hole.  If  one  tube  is  ten  times  as  large  as  another, 
and  both  have  the  same  depth  of  water  in  them,  the  first 
will  contain  ten  times  as  much  water  as  the  second,  and 
the  surface  of  the  water  will  be  ten  times  as  great. 

Exp.  29.  Withdraw  the  piston  to  the  top  of  the  tube, 
measure  the  length  of  the  tube  thus  filled  with  water,  and 
also  the  depth  of  the  water  in  the  Apparatus.  Push  the 


28 


INDUCTIVE  PHYSICS. 


Exp.  29. 


piston  to  the  bottom  of  the  tube,  and  find  how  much 
the  water  from  the  tube  increases  the  depth  of  water  in 
the  Apparatus.  If  the  piston  is  not 
air-tight,  fill  the  tube  and  the  Appara- 
tus with  water,  cork  the  tube,  then 
pour  nearly  all  the  water  from  the  Ap- 
paratus, and  measure.  Uncork  and 
measure  again. 

INFERENCES.  1.  The  Apparatus  is  how 
many  times  the  size  of  the  tube  ?  2.  AVith 
one  pound  pressure  on  the  surface  of 
water  in  the  tube,  how  many  would  be 
required  on  the  water  surface  in  the  Ap- 
paratus to  balance  ?  See  Aux.  8. 

Exp.  3O.    Fill  both  the   Apparatus 
and  the  tube  with  water,  as  in  EXP.  22, 
and  tie  sheet  rubber  over  the  mouth.     Place  weights  <>f 
four  or  five  pounds  on  the  Apparatus,  and  blow  into  the 
tube. 

INFERENCES.  1.  Why  can  you  lift  so  much  with  so  little 
force  ?  2.  How  would  you  determine  the  number  of  pounds 
lifted  by  an  ounce  of  force  applied  through  the  tube  ?  By 
blowing  through  the  tube  you  can  apply  only  about  an  ounce 
of  pressure. 

PRACTICAL    APPLICATION. 

This  picture  illustrates  the  "  hydrostatic  "  or  water- 
press,  a  machine  which  enables  one  with  but  little  force 
to  exert  great  pressure.  A  pump  stands  in  an  open  t;mk 
of  water.  In  the  pump,  a  little  above  the  level  of  the 
water  in  the  tank,  is  a  closed  door-shaped  valve,  which 


WATER   EXPERIMENTS. 


29 


opens  upward  when  the  piston  is  pulled  up,  allowing 
water  to  enter  and  fill  the  pump.  Why  it  does  so,  you 
probably  cannot  see  at  present,  but  you  will  when  you 
study  the  next  subject,  —  Air.  In  the  pipe  connecting 
the  pump  and  the  press  is  a  valve  opening  towards  the 
latter.  When  the  piston  of  the  pump  is  pushed  down,  of 
course  the  pump-valve  closes ;  and  as  the  water  cannot  be 


Fig.  8. 

pushed  out  the  way  it  came  in,  it  goes  through  the  other 
door  to  the  press. 

INFERENCE.  Upon  what  fact  about  liquids  does  the  great 
power  of  this  press  depend  ? 

While  performing  the  previous  experiments,  you  have 
learned  something  about  the  so-called  physical  properties 
of  water.  You  can  also  mention  one  force  that  has  a 
great  deal  to  do  with  these  properties.  There  are  other 
forces  always  operating  which  you  will  discover  in  connec- 
tion with  the  study  of  the  next  subject,  —  Air.  Before 
beginning  the  study  of  air,  it  would  be  advisable  that  you 
state  again,  clearly  and  briefly,  all  you  have  discovered 
about  water. 


AIR    EXPERIMENTS. 


Bxp.  31.   Plug  holes  in  the  Apparatus,  and  all  but  one 
in  the  stopper;  in  this  insert  funnel,  and  fill  it  with  \\aU-i. 
OBSERVATION  AND  INFERENCE. 


Exp.  31. 


Exp.  32. 


Exp.  32.  With  bent  tube  in  the  side  of  the  Apparatus, 
opening  under  water  in  a  dish,  fill  the  funnel  with  water. 

OBSERVATION  AND  INFERENCE. 

Bxp.  33.  Float  the  wooden  ball  on  water,  invert  the 
Apparatus  or  a  tumbler  over  it,  and  press  it  well  down 
into  the  water. 

OBSERVATION. 

INFERENCES.  1.  What  fact  about  air  do  these  three  experi- 
ments teach  ?  2.  Compare  with  the  first  learned  about  water. 
30 


AIR    EXPERIMENTS. 


31 


Exp.  34.  Push  the  inverted  Apparatus  down  into  the 
water.  Blow  gently  through  the  tube,  and  you  have  a 
miniature  diving-bell. 

INKKKKNCK.  Why  does  .not 
the  upward  pressure  of  the 
water  force  it  up  into  the  Ap- 
paratus ?  See  Aux.  9. 

NOTE.  —  The  lack  of  delicate 
scales  makes  EXP.  35  impossible  in 
most  schools,  hence  the  teacher 
should  construct  Aux.  10,  and  use 
instead. 

Exp.  35.  Plug  every 
hole  in  the  Apparatus  (or 
use  a  large  bottle),  and 
every  hole  but  one  in  the 
stopper  ;  in  this  insert  a 
short  glass  tube,  and  attach 
to  it  a  short  rubber  tube 
with  a  plug  in  the  end. 
Balance  the  Apparatus  or  E*P  34. 

bottle  on  scales,  then  remove 

the  plug,  and  suck  out  all  the  air  you  can.  Pinch  the 
tube  to  prevent  air  entering  whenever  you  stop  to  rest 
your  throat,  and  stop  sucking  when  you  can  exhaust  no 
more  air ;  also  be  careful  not  to  let  water  from  your 
mouth  enter  the  tube,  as  a  few  drops  might  spoil  the  ex- 
periment; replace  the  plug,  and  return  the  Apparatus  or 
bottle  to  its  scale-pan.  If  the  scales  are  delicate  enough, 
and  you  have  performed  the  experiment  well,  it  will 
weigh  less  than  before. 


32 


INDUCTIVE  PHYSICS. 


INFERENCE.    Compare  with  this  the  second  fact  learned 
about  water.     For  cheap  but  excellent  home-made  apparatus 
for  this  experiment  see  Aux.  1O. 

Exp.  36.  Insert  the  stopper  tightly 
in  the  Apparatus,  pour  mercury  into 
the  hole  partly  filled  by  the  rattan  plug, 
and  suck  air  from  the  Apparatus.  (Do 
not  allow  mercury  to  touch  a  gold  ring.) 

INKKKKNCK.  What  causes  the  mercury 
shower  ?  See  Aux.  11. 

Exp.  37.  Fill  the  Apparatus  with 
water,  and  place  a  piece  of  card  over 
the  mouth.  With  one  hand  hold  the 
card  in  place,  while  inverting  the  Apparatus  with  the  other 
over  a  dish,  to  catch  the  water  if  the  experiment  should 
fail.  Remove  your  hand  from  the  card.  In  the  sanu1  way 
repeat  with  disk  of  wood,  metal  (iron,  zinc,  or  lead),  and 
glass.  Repeat,  using  a  piece  of  wet  cheese-cloth,  or  silk 
veiling,  and  wire  netting.  Repeat  again,  and  uncap  the 
jet-tube  near  the  bottom  of  the  Apparatus. 

INFEKENCE.    See  Aux.  12. 

Exp.  38.     Tie     sheet    rubber 
over  the  mouth  of  the  Apparatus, 
and  attach  the  long  rubber  tube 
to  either  side  hole.     Suck  a  lit- 
tle air  from  the  Apparatus,  and 
pinch   the    rubber  tube  to  pre- 
vent  its   returning.     Turn   the 
mouth  of  the  Apparatus  in  every  direction. 


Exp.  38. 


AIR   EXPERIMENT*.  33 

INFERENCES.  1.  What  more  about  air  pressure  does  this 
teach  you  than  did  Exi«s.  36  and  37  '.'  2.  Compare  with 
water  pressure.  3.  What  force  causes  it  ? 

Exp.  39.  Use  your  hand  instead  of  the  sheet  rubber, 
and  suck  out  all  the  air  you  can.  Turn  your  hand  over 
and  in  every  direction.  If  the  experiment  is  well  done, 
the  Apparatus  will  not  fall  off.  You  can  hardly  pull 
it  off. 

INFERENCE.    Why  ? 

Exp.  4O.  Suck  the  air  from  the  small 
bottle,  and  stick  it  to  the  upper  lip,  or 
else  try  the  next  experiment  instead. 

Exp.  41.    Wet  a  jet-tube  rubber  cap, 
squeeze  it  with  your  fingers  or  teeth,  and 
press  the  tongue  against  the  open 
end.      If  well  done,  you  cannot 
shake  it  off. 

INFERENCE.    Why  ? 

Exp.  42.  Fill  the  Apparatus 
with  water,  and  tightly  insert  the 
stopper  with  all  the  holes  open, 

after  which  plug  them  with  the  shot.  Though  the  stop- 
per may  be  easily  twisted  around  in  the  Apparatus,  it  is 
pulled  out  with  great  difficulty. 

INFERENCE.    Why  ? 

Exp.  43.  Wet  the  inside  of  the  tube  and  wrapping  on 
the  piston-rod.  Pull  up  the  piston. 

INFERENCE.    Why  does  water  follow  it  in  the  tube  ? 


34 


1NDUVT1  VK    1  '11  I  >  l(  '$. 


Exp.  44. 


Exp.  44.  (To  be  omitted  if  tlie  pupil  is  not  willing 
to  pound  his  finger  a  little.)  Wet  the  inside  of  the  tube 
and  the  rubber  on  the  rod,  then  insert 
the  rod,  and  hold  the  Apparatus  as 
illustrated.  Press  the  finger  tightly 
against  the  end  of  the  tube,  pull  the 
rod  about  half-way  out,  and  holding  it 
in  the  centre  of  the  tube,  let  go  of  it. 

Exp.  45.  This  experiment  illustrates 
how  we  pump  water.     Put  a  valve  (a 
short  slit  rubber  tube 
with  shot  in  one  end) 
on  one   end  of   a  C- 
inch  tube,  but  not  far 
enough  to  open  the  slit.     With  pack- 
ing on  the  other  end,  insert  the  tube 
into  the  bottom   hole    of    the   Appa- 
ratus   from    the    mouth.       Push    it 
through  carefully,  so  as  not  to 
open  the  slit  till  you  can  seize 
the  end  below,  and  draw  it  the 
rest  of  the  way.     Connect  the 
other  valve,  slit  downward,  to 
the    Apparatus    as    illustrated, 
and  tie   the  sheet  rubber  over 
the  mouth.     Seize  the  sheet  rub- 
ber in  the  centre,  pull  up  and 
push  down  alternately,  and  pump 
water  from  a  bottle  or  pail. 

INFERENCE.    Explain   the  best  you  can  now,  and   better 
after  you  learn  more  about  air.     See  Aux.  13. 


Exp.  45. 


AIR   EXPERIMENTS. 


35 


Exp.  46.    This  experiment  illustrates  how  we  breathe. 
The  Apparatus  represents  the  chest  cavity  ;  the  rubber  bal- 
loon, the  lungs.     Alternately  pull  out 
and  push  in  the  centre  of  the  sheet 
rubber  tied  over  the    mouth  of  the 
Apparatus.     Of  course  in  our  bodies 
there  is  no  such  space  surrounding  the 
lungs  filled  only  with  air,  also  the  chest 
is  enlarged  by  a  different  method,  but  the 
physical  fact  is  the  same.     Did  you  ever 
see  a  bellows  for  blowing  a  fire  ?     Study 
the  illustration  of  one  on  next  page. 

INFERENCES.  1. 
Do  we  "draw  in"  air 
through  the  nose  or 
mouth  when  we 
breathe,  or  simply  en- 
large our  chest  cavity, 
and  let  nature  do  the 
rest?  2.  Do  you 
think  there  is  any  such  thing  as  suc- 
tion? 

Exp.  47  is  nearly  the  same  as 
EXP.  46,  only  it  is  performed  by 
using  water  instead  of  sheet  rub- 
ber. First  fill  the  balloon  with  air, 
then  alternately  lower  the  Appa- 
ratus, into  water  a  short  distance, 
and  withdraw  it.  See  Aux.  14. 


E xp.  46. 


Exp.  47. 


Exp.  48.     Tie   the   sheet  rubber  over  the   mouth   of 
the  Apparatus,  and  put  a  je1>tube  into  each  hole,  as  in 


36  INDUCTIVE  PHYSICS. 

EXP.  25.     Strike  on  the  rubber,  and  feel  the  air  at  the 
holes. 

INFERENCES.  1.  Compare  with  pressure  transmitted  by 
water.  See  Aux.  15.  Compare  what  you  have  learned  about 
air  with  what  you  learned  about  water.  2.  What  like  prop- 
erties do  they  possess?  3.  Have  you  discovered  anything 
which  air  will  do  that  water  will  not  ?  4.  If  so,  tell  what  it 


Fig.  9. 


is,  and  where  you  discovered  it.  5.  If  you  have  not,  after 
telling  in  what  respects  air  is  like  water,  tell  as  well  as  you 
can  how  it  differs  from  water.  Then  try  the  following  ex- 
periments, explaining  all  you  can  by  means  of  facts  already 
discovered,  but  keep  your  eyes  open  for  new  facts  about  either 
air  or  water. 

Exp.  49.  Connect  the  Apparatus  and  tin  can  by  means 
of  the  rubber  tube.  Put  the  stopper  into  the  Apparatus, 
and  fill  the  can  with  water.  Fill  both,  put  a  stopper  into 
the  Apparatus,  and  empty  the  water  from  the  can. 


AIR    EXPERIMENTS. 


£ xp.  49. 


INFERENCE.    Why  does  not  the  water  run  in  either  case  ? 

Exp.  5O.    1.    With  the   bottom  hole  open,  lower  the 
inverted  Apparatus  into  a  dish  of  water  till  it  is  full,  then 


Exp.  50. 


plug  the  hole,  or  cover  it  with  the  ball  of  your  finger,  and 
lift  it  nearly  out.  2.  While  full  of  water,  and  held  with 
the  mouth  only  under  water,  open  the  bottom  hole. 


38  INDUCTIVE  PBTSICS. 

INFERENCES.  1.  Why  did  not  the  water  run  out  ?  2. 
Why  did  the  water  run  out  ? 

Exp.  51.  With  mouth  and  bottom  hole  open,  and  the 
Apparatus  erect,  sink  it  beneath  the  surface  in  a  dish  of 
water,  and  when  filled,  cover  the  mouth  with  a  card,  held 
firmly  in  place.  Then  lift  it  nearly  out  of  the  water. 

INFERENCES.  1.  Does  the  water  press  up  against  the 
card  ?  2.  If  so,  which  presses  the  harder,  water  underneath 
or  air  on  top  ?  Be  sure  to  write  your  opinion  before  trying 
the  next  experiment.  Be  careful,  for  even  older  pupils  fre- 
quently make  a  mistake  in  answering  this  question  when  not 
allowed  to  find  out  by  experiment. 

Exp.  52.  Repeat  the 
last  experiment,  using,  in- 
stead of  the  card,  sheet 
rubber,  tying  it  firmly  over 
the  mouth  of  the  Appa- 
ratus. 

INFERENCES.  1.  Did  you 
answer  the  question  in  EXP. 
51  correctly  ?  2.  Explain 
this  one  as  fully  as  possible, 
remembering  that  the  elas- 
ticity of  the  rubber  is  one 
force  operating  to  produce 
the  balance. 

Exp.  53.  Fill  the  4-inch  jet^tube  under  water,  and 
with  finger  pressing  against  the  larger  end,  lift  it  out  of 
water.  Raise  the  finger  a  trifle,  and  replace  it  quickly. 
Repeat  till  the  water  has  nearly  all  dropped  from  the 


AIR  EXPERIMENTS. 


39 


tube.     Try  a  tube  with  large  opening  at  each  end.     Try 
the  largest  tube. 

INFERENCES.  1.  Explain  carefully.  2.  Explain  also  why 
the  water  does  not  all  run  out.  3.  If  the  water  did  not  adhere 
to  the  glass,  would  or  would  it  not  all  run  out  ? 

Exp.  54.  Use  all  the  different 
sized  tubes  you  have  as  in  EXP.  53. 
Also,  wet  them  inside,  and  hold 
them  with  one  end  in  water  and 
the  other  open. 

INFKKENCES.  1.  How  does  the 
length  of  the  water  column  compare 
with  the  size  of  the  tube  ?  2.  Is  it 
not  the  same  force  that  makes  a  post- 
age stamp  stick  to  the  envelope,  or 
chalk  stick  to  the  blackboard  ?  3. 
Are  you  not  using  the  same  force 
when  answering  these  questions  in 
your  books  ?  4.  Give  other  examples.  We  call  the  force 
which  causes  particles  not  alike  to  stick  to  each  other,  ad- 
hesion ;  but  if  the  particles  which  stick  together  are  alike, 
we  call  the  force  cohesion.  5.  Which  force  do  you  overcome 
when  you  break  a  stick  or  a  string?  6.  Do  both  of  these 
forces  act  in  holding  water  in  a  glass  tube  ?  In  tubes, 
especially  when  they  are  small,  whether  glass  or  not,  we 
call  the  force  capillary  attraction,  from  the  Latin  word  ca- 
pillifs,  meaning  hair.  7.  Now,  using  the  word  cohesion, 
explain  one  difference  between  solids  (such  as  glass,  wood, 
iron,  etc.)  and  liquids  (such  as  water,  oil,  etc.).  8.  When 
water  becomes  a  solid,  or  ice,  has  it  more  or  less  cohesion  ? 
9.  What,  force  appears  to  be  the  opposite  of  cohesion  ?  10. 
What  changes  ice  to  water  ?  See  Aux.  16. 


Exp.  53. 


40 


IND  UCTIVE  PJI  YSIf ' s. 


Bxp.  55.  With  a  clean  disk  of  glass  and  one  oi  metal 
(or  two  of  glass),  a  match,  and  two  rubber  bands,  con- 
struct the  apparatus  illustrated.  Immerse  in  water  to  wet 
the  inner  surfaces  of  the  plates,  then  stand  in  shallow 
water. 

INFERENCES.  1.  Illustrate  with  a  drawing,  and  explain. 
2.  Look  also  for  a  result  of  the  same  force  in  a  tumbler  of 

water. 


Exp.  55. 


Exp.   56. 


Exp.  56.  Place  a  small  tube  in  the  mercury  in  the 
small  bottle.  Also  use  the  tube  with  mercury  as  a 
dropper. 

INFERENCES.  1.  Illustrate  with  drawings.  2.  Compare 
the  two  forces  in  this  case  with  the  same  in  case  of  water 
and  glass. 

Bxp.  57.  Fill  the  equal-arm  U-tube  with  water;  with 
the  finger  cover  one  end,  invert,  and,  holding  it  perpen- 
dicularly, remove  the  finger. 

INFERENCES.  1.  Infer  why  the  water  does  not  fall  out. 
2.  Name  all  the  forces  you  can  that  are  operating  in  this 


AIR  EXPERIMENTS. 


41 


experiment.  3.  Do  they  all  assist  in  holding  water  in  the 
tube,  or  not  ?  Repeat  the  experiment,  using  U-tube  with 
unequal  arms.  Repeat  again  with  first  U-tube,  inclining  it 
till  the  water  runs  out. 

Exp.  58.  Fill  the  U-tube  with  water,  and,  placing  a 
finger  over  one  end,  invert  and  hang  it  over  the  edge  of 
the  Apparatus  or  dish  full  of  water,  and  remove  the 
finger.  Raise  it  until  the  water  runs  out  in  drops,  and 
finally  not  at  all.  Experiment  till  you  see  how  to  make 
it  run  either  slowly  or  rapidly  at  pleasure. 


Exp.  57. 


Exp.  58. 


INFERENCES.  1.  Infer  the  difference  in  conditions.  2. 
Test  your  statements  by  using  the  unequal-arm  U-tube,  to  see 
if  you  gave  the  conditions  correctly.  3.  Explain  carefully 
what  starts  the  water  running,  and  what  keeps  it  running. 

4.  If  there  were  no  air  in  the  room,  would  it  run  at  all  ? 

5.  If  you  think  it  would,  tell  how  and  why.     This  instrument 
is  called  a  siphon,  and  it  has  a  great  many  forms.     Experi- 
ment with  any  other  you  find  in  your  set.     Make  one  with 
your  long  rubber  tube,  and  experiment  with  it  in  different 


INDUCTIVE  PHYSICS. 


positions.     6.    How  many   of   the   tubes    in 
Apparatus  "  set,  can  you  use  as  siphons  ? 


the   "100   in    1 


f  xp.  59. 

Exp.  59.  Use  the  same  apparatus  as  in  EXP.  58. 
with  the  addition  of  the  tin,  and,  after  the  water  has 
reached  the  same  level  in  each  dish,  raise  first  one,  then 
the  other,  and  watch  the  changing  direction  of  the  flow. 

INFERENCES.  1.  Which',  in  each  case,  is  the  longer  arm  of 
the  siphon  ?  2.  The  length  of  each  arm  of  a  siphon  is  the 
perpendicular  distance  between  the  highest  point  of  water  in 
it,  and  what  other  point  or  level  ? 


Exp.  60. 


Exp.  6O.  Fill  one  dish  with  water,  and  as  soon  as  it 
begins  to  run  into  the  other,  raise  the  centre  of  the  rubber 
tube  as  high  as  possible  above  the  dishes. 


AIR  EXPERIMENTS. 


43 


INFERENCES.  1.  What  starts  the  flow  ?  2.  What  keeps 
it  going  ?  3.  Does  the  force  that  keeps  it  running  affect  it 
when  the  tube  lies  on  the  table  or  hangs  over  the  edge  ?  4. 
In  which  of  the  three  cases  would  it  flow  just  the  same  if 
there  were  no  air  in  the  room  ? 

Exp.  61.  Insert  the  end  of  the  longer  arm  of  U-tube 
into  the  bottom  hole  of  the  Apparatus  till  the  bend  is 


Exp.  61. 

below  the  mouth,  and  fill  the  Apparatus  with  water.     This 
is  called  a  Tantalus  cup. 

INFERENCE. 

Exp.  62.  Fasten  the  Apparatus  and  tin  can  tightly  to- 
gether with  the  unequal-arm  siphon  and  a  half-inch  piece 
of  rubber  tubing  taken  from  the  pressure-gage  and  used 
as  packing  for  both.  Arrange  as  illustrated,  with  your 


44 


INI)  UCTI  YE  PII YSICS. 


finest  jet-tube  on  the  lower  end  of  the  rubber  tube  to  sup- 
ply a  small  but  constant  stream  of 'water  to  the  "  Tantalus 

cup,"  and  you  will  have  an 
intermittent  flow  from  the 
cup.  Should  the  jet^tube 
be  too  large  to  allow  the 
discharge  from  the  cup  to 
intermit,  diminish  the  water- 
supply  by  pinching  the  tube 
at  the  right  time. 

INFERENCES.  1.  How 
many  siphons  are  there  in 
t  h  i  s  experiment  ?  2.  In 
what  essential  respect  do 
they  agree,  and  in  what  do 
they  differ? 

An  intermittent  spring 
is  one  that  does  not  flow 
all  the  time,  but  has  alter- 
nate periods  of  flow  and 
rest.  The  periods  of  rest 
come  generally  after  a  long 
dry  spell,  and  sometimes 
not  till  the  dry  spell  has 
ended  and  it  is  ii^nin 
rainy  weather.  Fig.  10  il- 
lustrates the  conditions  of 

a  hill  from  which  there  issued  such  a  spring,  until  a 
railway  was  cut  through  it  and  the  spring  was  destroyed. 
In  the  hill  was  a  cavern  seamed  with  numerous  small 


£  xp.  62, 


AIR   EXPERIMENTS. 


45 


cracks  through  which  ran  the  water  that  filled  it.     The 
water  flowed  out  through  a  single  arched  opening. 


Fig.  10. 

INFERENCES.    1.    Explain  how  the  flow  became  intermit- 
tent under  varying  conditions  of  weather.     2.    Under  what 
conditions  might  a  drought  come  and  go  without  the  flow  of 
water  ceasing  ?      3.    If  it   stopped    flowing, 
how  much  rain  or  melted  snow  would  have 
to  find  its  way  into  the  cave  before  it  started 
again  ? 

Bxp.  63.     Instead    of    the    apparatus 
shown  in  the  cut,  use  your  pail,  long  rub- 
ber tube,  and  a  short  jet-tube,  as  in  EXP. 
62,  to  construct  and  operate 
a  siphon  fountain.     Vary  the 
height  of  the  jet  of  water  by         /r — 
raising  and  lowering  the  jet-       ^— '• 
tube. 

INFERENCE. 


Exp.  63. 


46 


INDUCTIVE  PHYSICS. 


Exp.  64.  Place  a  short  tube  in  one  hole  of  the  stopper 
and  a  6-inch  tube  in  the  bottom  hole  of  the  Apparatus. 
Fill  the  Apparatus  with  water,  and  insert  the  stopper. 
Place  your  finger  over  the  end  of  the  tube  beneath  the 
Apparatus,  and  invert.  Use  the  bottle  dropper  as  you 
did  the  tube  in  EXP.  53. 

INFERENCE. 


Exp.  64. 


Exp.  65. 


Exp.  66. 


Exp.  65.  If  the  Apparatus  and  tul>e  are  full  of  water, 
and  you  uncap  the  upper  jet-tube,  how  much  water  will 
run  out  ?  This  is  a  good  test  of  your  previous  work  on 
air  pressure.  Answer  first,  then  verify  by  experiment. 

INFERENCE. 

Exp.  66.  Place  in  any  position,  and  suck  air  from 
the  Apparatus. 

INFERENCES.  1.  Distinguish  between  the  force  that  fills 
the  rubber  bag  in  this  case  and  in  "  how  we  breathe  "  (Exi». 
46).  2.  How  is  the  air  withdrawn  from  the  Apparatus  ? 
3.  What  forces  it  from  the  bottle  into  the  rubber  balloon  ? 


AIR   EXPERIMENTS. 


47 


Exp.  67.  The  same  bottle  used  in  the  previous  experi- 
ment, and  to  be  used  in  the  next,  will  answer  for  this  also. 
However,  the  taller  the  bottle,  the  prettier  the  experiment. 
Suck  air  from  the  Apparatus,  observing  what  is  happen- 
ing to  the  air  in  the  bottle  at  the  same  time.  Pinch  the 
tube,  rest  your  throat,  and  suck  again  till  you  remove  as 
much  as  you  can  ;  then  let  go  the  rubber  tube. 

INFERENCE.  Explain  each  part  of  the  experiment,  that  is, 
the  operation  of  the  fountain,  and  the 
process  of  preparing  conditions  neces- 
sary for  its  success. 


Exp.  67. 


Exp.  68. 


Exp.   69. 


Exp.  68.    Fit  a  jet-tube  tightly  to  the  small  bottle,  and 
put  it  inside  the  Apparatus.     Pour  in  a  little  water,  cork 
tightly,  and  suck  out  the  air. 
.     INFERENCE. 

Exp.  69.    With  the  short  thick-walled  rubber  tube  on 
the  large  end  of  the  jet-tube,  suck  the  air  from  the  Appa- 


INDUCTIVE  PHYSICS. 


ratus  (or  bottle  and  attachment  No.  6)  ;  pinch  the  rubber 
while  transferring  the  end  in  the  mouth  to  a  dish  of  water, 
then  release  it. 

INFERENCES.  1.  How  much  of  the  air  did  you  get  out? 
(After  a  little  practice  you  can  easily  exhaust  nine-tenths  <! 
it.)  2.  Do  you  draiv  it  out  ?  3.  What  forces  it  out  ? 

Bxp.  7O.  Fill  the  Apparatus  or  bottle  with  water, 
tightly  insert  the  stopper  with  holes  open,  after  which  put 
a  6-  or  8-inch  tube  through  one  hole,  plug  the  others  with 
shot.  Try  to  suck  out  water. 

INFERENCE.     Why  cannot  you  do  so  ? 

Bxp.  71-  With  but  little  water  in  the 
Apparatus,  and  with  the  tube  reaching  into 
the  water,  try  again. 

INFERENCES.  1.  Why  can  you  get  water 
now?  2.  How  does  air  differ  from 
water  as  regards  the  cohesive  force 
between  its  particles  ?  3.  In  place 
of  the  cohesive  force,  what  kind  of 
a  force  does  air  possess?  4.  How 
does  it  act  compared  with  cohesion  ? 
5.  Compare  with  discussion  of  Kxr. 
54.  See  Aux.  17. 

Exp.  72.  With  a  little  water 
in  the  Apparatus,  insert  in  the 
stopper  the  longest  jet-tube  and  a 
short  glass  tube  connected  with 
the  long  rubber  tube,  and  hang 
them  upon  the  edge  of  a  jar  or  pail  of  water. 

INFERENCE.  Explain  and  name  the  fountain  by  use  of 
the  principles  employed. 


AIR   EXPERIMENTS. 


49 


Exp.  73.  Place  the  short  heavy  rubber  tube  a  very 
short  distance  on  the  small  end  of  long  jet-tube  reaching 
into  water  in  the  Apparatus  or  a  large  bottle.  Blow  as 
much  air  as  possible  into  the  Apparatus,  pinch  the  rubier 
tube  while  removing  it  from  the  mouth,  and  pull  it  off 
the  jet-tube. 

INFERENCE.  What  tico  properties  of  air  not  possessed  by 
water  does  this  experiment  show  ? 


Exp.  74.  Blow  through  the  rubber  tube,  thereby  mak- 
ing a  miniature  fire-engine.  See  Auxs.  18  and  19. 

Exp.  75.  This  is  called  in  the  laboratory  a  "blow- 
bottle"  or  "wash-bottle."  It  is  used  to  supply  a  small 
stream  or  a  few  drops  of  water  to  a  vessel,  or  to  withdraw 
the  same.  Construct  it  as  illustrated,  fill  with  water, 
and  use  it  for  both  purposes  by  filling  and  emptying  one 
of  your  small  bottles. 


50 


INDUCTIVE  PHYSICS. 


INFERENCE.  Explain  the  principle  in  each  method  of 
using  it. 

Bxp.  76.  Connect  the  long  rubl>er  tube  to  a  side  hole 
of  the  Apparatus.  Wet  the  stopper,  and  insert  it  not  very 
tightly,  then  blow  hard  through  the  tube.  See  Aux.  20. 

Bxp.  77.    Partly  fill  the  small  bottle  —  "  bottle  diver  " 
—  with  water  until  it  floats  inverted,  with  the  bottom  just 
at  the  surface  of  water  in  dish.      Transfer 
it    to  the   Apparatus  or  large  bottle  full  of 
water  without  changing  the  amount  of  water 
in   the  small  bottle.     Tie    the   sheet  rubber 
over  the  mouth.     Press  on  the  sheet  rubl>er 
enough  to  send  the  bottle  diver  to  the  bottom, 
then  remove  the  pressure.     If  the  small  bot- 
tle is  delicately  balanced  by  having  exactly 
enough  water  in  it,  the  sheet  rubber  is  not 
needed ;  use  the  palm  of  the  hand  instead. 
INFERENCE.     Explain  every  step  of  the  experiment.     See 
Auxs.  21  to-  29. 

Bxp.  78.    A  little  care  is  necessary  in  order  to  get  the 
tube  exactly  centred  over  the  bottom  hole, 
and  near  enough  to   it  to  work  well.       It 
should  be  as  near  as  possible  without  enter- 
ing the  hole.     To  give  the  necessary  incli- 
nation to  the  tube,  crowd  the  rub- 
ber stopper  in   more   on  one  side 
than  the  other;  it  is  easier  to  use 
a  common  cork  with  a  hole  in  the 
centre.    The  tumbler  or  bottle  used 
instead  should  be  quite  full  of  wa- 
ter.    Blow  hard  through  the  tube,  and  water  as  well  as 
air  is  blown  out. 


Exp.  77. 


AIR  EXPERIMENTS. 


51 


INFERENCES.  1.  What  must  be  the  condition  of  the  air 
in  the  Apparatus  before  water  can  rise  into  it  ?  See  Auxs. 
3O  and  31.  2.  What  produces  that  condition  ?  3.  How  ? 

Exp.  79.    Blow  hard  through  the  tube  held  in  a  hori- 
zontal position,  with  wooden  ball  held 
an  inch  or  more  above  the  opening 
near  the  bend;  let  go  the  ball,  and 
keep    it   floating  in    mid-air.     After 
acquiring  some  skill  with  the  tube  in      ^ 
that  position,  incline  it  as  shown  in 
the  picture,  and  see  how  much  you 
can  do  so,  still  keeping  the  ball  in 
the  air.     See  Auxs.  32  and  33. 


Exp.  79. 


INFERENCE. 


SUPPLEMENTARY 
GRAMMAR-SCHOOL  WORK. 


QUANTITATIVE   STUDY   OF   PRESSURE,    COMPRESSIBILITY, 
AND   EXPANSIBILITY   OF   AIR. 

TO   THE   TEACHER. 

THIS  quantitative  work  presupposes  that  the  pupil  has  mastered 
the  qualitative  work  preceding  it,  and  that  he  has  not  only  obtained 
the  facts,  but  that  it  was  done  in  the  proper  manner,  so  that  he  is  able 
to  think  for  himself,  and  to  use  the  facts  previously  obtained  as  instru- 
ments of  thought.  These  experiments,  we  know  from  experience,  are 
none  too  hard  for  grammar-school  pupils  who  have  laid  the  proper 
foundation  for  them  ;  and  the  pupil's  work  on  the  first  five,  especially 
that  on  the  fourth  and  fifth,  will  determine  whether  he  is  prepared  to 
advance. 

Bxp.  8O.  Join  the  Apparatus,  a  glass  connecting-tube, 
the  long  rubber  tube,  and  a  jet-tube.  Hold  it  as  illus- 
trated. Fill  the  Apparatus  with  water,  and  when  it  be- 
gins to  flow  from  the  jet-tube  insert  the  rubl>er  stopper. 
If  convenient,  connect  two  rubber  tubes,  stand  upon  -a 
table,  step-ladder,  or  hall-stairs,  and  repeat  the  experi- 
ment. 

INFERENCES.  1.  Why  cannot  you  determine  with  rubber 
tubes  how  high  a  column  of  water  air-pressure  will  sustain  ? 
2.  Could  you  determine  this  with  a  glass  tube  if  it  were  long 
enough  ? 

52 


SUPPLEMENTARY  GRAMMAR-SCHOOL    WORK.       53 


Exp.  81.  (This  experiment  should  usually  be  done 
by  the  teacher.)  Take  the  barometer  from  its  permanent 
place  against  the  wall  or  window-casing,  and  hold  it  as 


Exp.  80. 


Exp.  81. 


shown  in  "  a."  Call  attention  to  the  fact  that  the  long 
glass  and  the  short  rubber  tube  are  full  of  mercury,  and 
that  no  air  can  enter  the  tubes  except  at  the  open  end. 
Slowly  invert  the  long  tube,  while  the  pupils  watch  the 
upper  end  of  it. 


54 


INDUCTIVE  PHYSICS. 


INFERENCES.  1.  Why  has  the  mercury  sunk  in  the  long 
tube,  and  risen  in  the  short  one  ?  2.  What  is  in  the  long 
tube  above  the  mercury  ?  3.  How  much  of  the  mercury  is 
balanced  by  air-pressure?  4.  How  deep  a  sea  of  mercury 
would  it  take  to  press  upon  the  earth  just  as  much  as  the  air 
presses  ?  5.  If  you  should  carry  this  barom- 
eter up  a  high  mountain,  and  the  difference 
in  the  length  of  the  columns  of  mercury  di- 
minish one-half,  how  much  of  the  air  would 
you  have  passed  above  ?  6.  That  much  in 
depth  or  weight  ?  7.  Why  not  the  same 
amount  in  both  depth  and  weight  ? 

Exp.  82.  Observe  the  length  of  the 
mercury  column  of  the  barometer,  at  least 
once  a  day,  and  make  a  record  of  it  on  a 
printed  calendar  or  in  a  table  of  your  own 
construction. 

INFERENCES.  1.  Infer  as  to  the  variation 
of  air-pressure.  2.  Can  you  discover  any  re- 
lation between  air-pressure  and  the  weather 
—  fair  or  stormy?  3.  Study  a  Signal  Ser- 
vice weather-map  in  this  connection. 

Exp.  83.  Pour  mercury  into  the  Ap- 
paratus until  it  stands  in  each  tul)e  one-half 
inch  or  more  above  the  rubber  connector. 
Pour  water  into  one  tube  until  it  is  13.5 

inches  deep.     Measure  the  height  of  the  mercury  column 

balanced  by  the  water. 

INFERENCES.  1.  Mercury  is  how  many  times  as  heavy  as 
water?  2.  How  high  a  column  of  water  will  air-pressure 
sustain  when  the  difference  in  the  mercury  columns  of  a 


Exp.  83. 


SUPPLEMENTARY  GRAMMAR-SCHOOL    WORK.       55 


barometer  is  30  inches  ?  3.  At  the  same  time,  what  would 
be  the  greatest  possible  distance  between  the  water  in  a  well 
and  the  lower  valve  in  a  lifting-pump  ?  4.  As  a  cubic  inch 
of  mercury  weighs  about  half  a  pound,  what  is  (to  the  near- 
est pound)  the  pressure  of  the  air  upon  every  square  inch  of 
the  sea  ?  5.  Why  is  it  not  the  same  upon  every  square  inch 
of  the  land  surface  of  the  earth  ? 

Review  Inferences  11  and  12  to  Ex  p.  16,  of  first  course 
(reprinted  below),  and  make  corrections  for  air-pressure  when 
barometer  stands  at  30  inches. 

"Exp.  16  —  INFEREXCKS.  11.  A  cubical  tin  dish  with  bottom  one 
foot  square  will  hold  02.5  Ibs.  of  water.  If  full,  what  is  the  pressure 
against  one  side  of  the  dish  ?  12.  What  is  the  total  water-pressure 
against  the  sides  and  bottom  ?"  3.  How  much  of  the  outward  is  bal- 
anced by  inward  pressure  ?  4.  What  is  the  upward  pressure  of  the 
water  at  its  surface  ? 

Exp.  84.  (Exr.  51  of  first  course.)  With  the  mouth 
and  the  bottom  hole  of  the 
"100  in  1  Apparatus  "  open, 
sink  it  in  a  disli  of  water. 
Cover  the  mouth  with  a  card, 
or  the  palm  of  your  hand,  and, 
holding  it  firmly  in  place,  lift 
the  Apparatus  nearly  out  of 
the  water. 

INFERENCES.  1.  Does  the  wa- 
ter press  upwards  against  the 
card  ?  2.  If  so,  which  presses 
the  harder,  water  underneath  or 

air  On  toP  ? 

NOTK.  —  Of  course  an  inverted 

tumbler  or  bottle  will  answer  just  as  well  as  the  Apparatus  for  this 
experiment. 


56  INDUCTIVE  PHYSICS. 

Imagine  that  you  have  an  Apparatus  as  many  times 
the  height  of  the  mercury  column  in  the  barometer  as 
mercury  is  times  as  heavy  as  water. 

INFERENCES.  1.  What  is  the  height  of  your  imaginary  Ap- 
paratus ?  2.  What  is  the  water-pressure  against  the  iinder 
side  of  the  card  ?  3.  What  is  it  against  the  bottom  of  the 
Apparatus  ?  4.  How  does  it  compare  with  outside  air-pres- 
sure, .25,  .50,  .75  way  from  the  bottom  to  the  top  ?  5.  How 
would  the  total  water-pressure  against  the  inside  compare 
with  the  total  air-pressure  against  the  outside,  if  inside  and 
outside  surfaces  were  exactly  equal  ?  6.  Make  the  above 
comparisons  with  an  Apparatus  of  the  same  height,  open  at 
the  top  and  closed  at  the  bottom.  7.  If  two  water-towers 
should  be  built  of  equal  strength  throughout,  with  exactly 
the  same  conditions  as  the  above  imaginary  pieces  of  Appa- 
ratus, —  i.  e.,  one  open  at  the  top  and  closed  at  the  bottom,  and 
the  other  closed  at  the  top  with  the  bottom  open  under  water, 
—  and  each  should  leak  soon  after  being  filled  with  water,  at 
or  near  which  end,  in  which  direction  (inwards  or  outwards), 
and  what  substance,  would  each  one  leak  ?  8.  Compare  care- 
fully in  regard  to  both  air-  and  water-pressure,  a  stand  pipe 
for  city  water-supply,  and  a  pipe  through  which  water  passes 
from  a  deep  well  to  the  lower  valve  of  a  pump.  9.  Explain 
now,  if  you  did  not  then,  why,  when  you  used  two  or  three 
tubes  connected  in  Ex  p.  1,  a  part  of  your  tube  flattened? 
10.  Why  cannot  you  pump  water  from  a  deep  well  through 
a  rubber  tube  ? 

Exp.  85.  (Exr.  37  of  first  course.)  Fill  with  Avater 
a  tumbler,  or,  better,  a  wide-mouthed  bottle,  cover  with  a 
card  or  disk  of  any  material  such  as  wood,  tin,  zinc,  lead, 
or  glass,  or  with  a  piece  of  cheese-cloth,  silk  veiling,  or 
wire  netting ;  then  invert,  holding  it  only  by  the  side. 


SUPPLEMENTARY  GRAMMAR-SCHOOL    WORE.      57 


INFERENCES.  1.  Do,  or  do  not,  the  same  conditions  of  pres- 
sure exist  as  in  above  apparatus  closed  at  the  top  ?  2.  Can 
you  hold  a  tumbler  full  of  water  so  that  either  water-pressure 
from  within  or  air-pressure  from  without  shall  be  the  greater  ? 
3.  If,  when  the  tumbler  is  inverted,  air-pressure  holds  up  the 
water,  of  course  you  do  not;  does  it  seem  as  heavy  then  as 
when  held  right  end  up  ?  4.  Explain  why,  if  it  does ;  and 
why  not,  if  it  does  not. 

Bxp.  86.  (Exp.  52  of  first  course.)  Same  as  EXP. 
84,  excepting  that  sheet  rubber  is  tied  over  the  mouth  of 
the  Apparatus. 

NOTE.  —  A  wide-mouthed  bottle,  the  taller  the  better,  with  a  hole 
in  the  bottom,  or  with  the  bottom  broken  off,  will  answer  in  place  of 
Apparatus  for  this  experiment,  and  also  for  Exi>.  84. 

Exp.  87.  Lower  the  Apparatus  sidewise  into  a  pail  of 
water,  and  stand  it  inverted 
upon  the  bottom  of  the  pail. 
Connect  the  long  rubber  tube 
at  one  end  with  the  pressure- 
gage,  and  holding  the  gage 
horizontally,  lower  it  into  the 
pail  till  water  reaches  the  sec- 
ond bend,  then  leave  it  held 
in  place  by  the  rubber  tube 
bending  over  the  edge  of  the 
pail.  Nearly  fill  the  8-inch 
jet-tube  with  water,  connect 
it  to  the  other  end  of  the  rubber  tube,  and  lay  it  upon  the 
table.  Lower  the  gage,  and  watch  the  effect  on  the  water 
in  the  jet-tube.  Raise  the  Apparatus  nearly  out  of  the 
water,  and  carefully  bring  the  funnel  arm  of  the  gage  up 


Exp.  87. 


58  INDUCTIVE  PHYSICS. 

into  it  to  the  top,  watching  the  effect  in  the  jet-tube.  If 
the  effect  is  not  exactly  the  reverse  of  that  produced  by 
lowering  the  gage,  the  experiment  was  not  well  done ; 
perhaps  the  rubber  tube  was  compressed,  thus  entirely 
changing  the  result.  Our  great  teacher  —  NATURE  — 
always  answers  the  same  questions  the  same  way. 

INFERENCES.  1.  Do,  or  do  not,  your  results  in  the  last  two 
experiments  confirm  your  inferences  in  Exi-.  84?  2.  Should 
they,  or  should  they  not  ? 

Exp.  88.  With  the  mercury  at  the  same  level  in  both 
tubes,  measure  the  length  of  the  column  of  air  confined  in 
the  closed  tube  ;  this  column  should  be  exactly  3  inches 
long.  Raise  the  open  tube  till  the  surface  of  the  mercury 
in  it  is  fifteen  inches  above  that  in  the  closed  tube.  Meas- 
ure the  same  confined  air,  and  place  the  result  in  Diagram 
1,  column  3,  on  the  next  line  below  figure  3.  Raise  the 
open  tube  till  the  difference  in  mercury-level  is  30  inches. 
Measure  the  same  air  again,  and  place  the  result  below 
the  last.  Return  the  open  tube  to  its  first  position,  then 
either  lower  it  or  raise  the  closed  tube  till  the  difference 
in  mercury-level  is  first  7.5,  then  15,  and  then  20  inches, 
each  time  measuring  the  confined  air,  and  recording  as 
before.  In  each  part  of  the  experiment  imagine  a  line 
drawn  horizontally  across  both  tubes  at  the  lower  mercury 
surface.  Of  course  the  mercury  below  that  line  in  either 
tube  is  balanced  by  the  mercury  below  the  line  in  the 
other  tube.  Now  study  to  determine  the  amount  of 
downward  pressure  at  the  level  of  that  line  in  the  open 
tube,  using  the  pressure  of  the  air  upon  the  surface  of 
the  mercury  (=  about  15  pounds  to  the  square  inch)  as  the 


SUPPLEMENTARY  GRAMMAR-SCHOOL    WORK.       59 


DIAGRAM   FOR   EXPERIMENT   88. 

AIR-PRESSURE     WITH     I5AROMETER     AT     30     INCHES     THE     UNIT 
OF    ALL    FORCES. 


N0, 

DIFFERENCE 

OF  AIK- 

FOBCE  ACTING  DOWNWARD 

FORCE  ACTING  DOWNWARD 

LEVEL. 

IN  TUBE. 

6 
5 

20  inches 

inches 

j  Expansive  force        = 
1  Weight  of  mercury  = 

f  Expansive  force       = 
Weight  of  mercury  = 

=  Pressure    of    air   in 
open  tube. 

I 

75    " 

(  Expansive  force 
I  Weight  of  mercury  = 

. 

' 

0 
15       " 

3     " 

|  Expansive  force  of 
<         enclosed  air        =  1 

=  Weight  of  mercury. 

:;  - 

30 

„ 

=  Pressure  of  air. 
=  Weight  of  mercury. 

Diagram  7. 


1 

2 

3 

4 

5 

NO 

AGAINST 

FOBOE  OF 

ENCLOSED 

ENCLOSED 

ENCLOSED 

ENCLOSED 

AIR. 

AIK. 

AIR. 

8 

B 

4 

., 

1 

1 

1 

1 

Diagram  2. 


60 


INDUCTIVE  PHYSICS. 


unit.  Place  the  number  representing  the  pressure  at  the 
left  of  the  sign  of  equality  on  the  proper  line  in  the  right- 
hand  column,  as  has  been  done  on  line  1.  If  a  part  of  the 
pressure  is  due  to  the  weight  of  mercury,  determine  how 
much  in  the  same  unit  (one  air-pres- 
sure), and  put  it  in  the  place  indicated. 
Of  course  the  total  downward  pressure 
at  the  level  of  that  line  must  be  the 
same  (on  the  same  amount  of  surface) 

V/fU/llll     in  ^ie  c^osec^ tu^  as  "l  tne  °Pen  tu^e- 

jj  j/jj/l'l  Determine  first  in  each  case  how  much 
1  ij  iji  of  it  is  due  to  the  weight  of  mercury, 
then  to  the  expansive  force  of  the  en- 
closed air,  and  indicate  each  in  its 
proper  place,  as  on  line  1.  See  if  the 
sum  of  the  two  is,  in  each  case,  equal 
to  air-pressure  and  weight  of  mercury 
in  the  open  tube. 

Diagram  2.  Of  course  the  enclosed 
air  must  in  each  case  press  down  against 
the  mercury  with  a  force  just  equal  to 
the  upward  pressure  of  the  mercury 
against  it.  Now  insert  in  column  2,  of 
Diagram  2,  the  proper  numbers  to  ex- 
press in  each  case  the  pressure  of  the 
mercury  against  the  enclosed  air.  In- 
sert in  column  3,  numbers  representing  the  resistant  force, 
in  4  the  density,  and  in  5  the  volume  of  the  same  air; 
1  represents  the  condition  of  each  at  the  beginning  of  the 
experiment.  Use  these  diagrams,  and  all  others,  only  to 
help  you  to  see  and  compare  the  facts  in  nature. 


SUPPLEMENTARY  GRAMMAR-SCHOOL    WORK.       61 

INFERENCES.  Examine  all  your  numbers,  and  think  care- 
fully what  they  represent,  and  see  what  comparisons  you  can 
make  between  pressure  exerted  upon  confined  air,  and  the 
expansive  force,  density,  and  volume  of  the  air.  Make  a  gen- 
eral statement,  giving  the  results  of  your  comparisons.  Ask 
yourself  and  answer  several  questions,  such  as  :  1.  If  pressure 
against  a  definite  amount  of  confined  air  is  doubled,  how  is 
each  —  its  expansive  force,  density,  and  volume  —  affected? 
2.  If  the  volume  of  confined  air  is  seen  to  increase  (with  no 
chance  for  other  air  to  leak  in),  what  must  be  true  of  its 
density,  its  expansive  force,  and  of  the  pressure  that  is 
exerted  against  it  ?  3.  What  would  you  do  to  confined  air 
to  treble  its  density  ?  and  if  this  were  done,  how  would  its 
volume  and  its  expansive  force  be  affected  ?  etc. 


BUOYANCY  —  SINKING  OBJECT. 

NOTE.  —  Careless  pupils  will  do  better  work  by  using  both  scale- 
pans  for  Ex  PS.  89  and  90,  the  same  as  for  91  and  92,  together  with 
a  small  dish  of  fine  shot  for  balancing  material,  handling  it  with  a 
small  tin  spoon.  With  careful  experimenters,  however,  the  Apparatus, 
suspended  with  the  copper  wire  made  to  slide  somewhat  snugly  along 
the  lever,  is  more  satisfactory. 

Exp.  89.  Set  up  the  Apparatus  as  shown  in  the  cut, 
with  the  small  bottle  filled  with  water  hanging  within 
about  half  an  inch  of  the  pan.  Carefully  slide  the  Appara- 
tus on  right  arm  (or  put  shot  into  the  scale-pan  instead) 
till  it  balances  the  bottles,  with  the  lever  as  nearly  hori- 
zontal as  your  eye  can  detect.  Lift  the  Apparatus  by  the 
upright  piece,  and  set  it  down  with  the  bottle  hanging  in 
the  tumbler  of  water. 

INFERENCES.  1.  Why  does  it  not  balance  with  the  beam 
of  the  scales  horizontal  as  at  first  ?  Lift  the  end  of  the  right 


62 


INDUCTIVE  PHYSICS. 


arm  of  the  lever.  2.  What  new  force  opposes  you,  and  what 
causes  it  ?  3.  You  exert  a  force  just  equal  to  the  weight  of 
what  ?  If  you  did  the  first  twenty-three  experiments  properly, 
you  can  answer  the  last  questions  correctly.  See  note  to  EXP. 
23.  Restore  the  Apparatus  to  the  first  position.  Pour  water 
into  the  tin  can  till  some  runs  out.  Remove  the  tumbler. 
Seize  hold  of  the  scales-beam  with  your  right  hand  at  the 
centre,  and  hold  it  horizontal  while  removing  the  wide-mouthed 
bottle  and  placing  it  under  the  water-spout.  Then  lift  the 


Exp.  89. 


Apparatus,  and  lower  the  bottle  into  the  tin  can,  and  when  the 
water  ceases  to  run,  return  the  wide-mouthed  bottle  with  its 
contents  to  its  scale-pan,  and  see  if  it  then  balances  with  the 
bottle  entirely  under  water.  If  it  does  not,  try  again.  Perhaps 
the  string  is  not  of  correct  length,  or  you  may  have  changed 
the  point  of  suspension  of  the  Apparatus,  or  perhaps  a  certain 
force  about  which  you  have  previously  learned  (4.  What  is 
it  ?)  interfered  with  the  discharge  of  water  at  one  time  more 
than  at  the  other,  hence  you  have  not,  by  a  few  drops,  the 
correct  amount  of  water  in  the  wide-mouthed  bottle. 


SUPPLEMENTARY  GRAMMAR-SCHOOL    WORK.       63 

5.  Why  does  an  object  weigh  less  in  water  than  in  air  ? 
6.  To  what  is  its  loss  of  weight  exactly  equal  ?  7.  Why  do 
the  scales  balance  with  the  bottle  under  water  now,  when  they 
did  not  with  the  bottle  hanging  in  the  tumbler  of  water? 
8.  Is  the  buoyancy  force  exerted  in  both  instances  ?  9.  Is  it 
always  exerted  upon  an  object  immersed  in  water  ?  10.  Which 
of  the  two  fundamental  facts  about  water-pressure  accounts 
for  it  ?  11.  Does  the  amount  of  buoyancy  depend  upon  the 
weight,  size,  or  shape  of  immersed  object?'  If  necessary,  ex- 
periment to  determine ;  but  if  you  find  it  necessary,  previous 
work  has  not  been  sufficiently  thorough.  12.  Does  any  fluid 
except  water  exert  this  force  upon  immersed  objects  ?  13. 
What  is  a  fluid  ?  14.  Which  weighs  the  more  (is  actually 
the  heavier),  a  pound  of  gold  or  a  pound  of  feathers ;  a  block 
of  wood  in  one  of  your  scale-pans  or  the  shot,  iron,  or  sand 
which  exactly  balances  it  in  the  other  ?  15.  Is  your  own 
weight  as  indicated  by  accurate  scales  absolutely  correct? 
16.  What  correction  does  it  need  ? 


BUOYANCY  -  FLOATING   OBJECT. 

Exp.  9O.  Use  the  block  suspended  by  a  pin  stuck  into 
the  centre  of  one  of  the  larger  sides,  and  proceed  as  in 
EXP.  89. 

INFERENCES.  1.  State  the  relation  between  the  weight 
of  the  block  and  the  weight  of  the  displaced  water.  2.  Make 
a  general  statement  that  will  apply  to  any  floating  object, 
even  to  an  ocean  steamer  or  a  man-of-war.  3.  Explain  the 
relation  of  buoyancy  to  the  weight  of  an  object  that  floats 
and  of  an  object  that  sinks.  4.  As  a  given  quantity  of  ocean 
water  is  heavier  than  the  same  quantity  of  river  water,  what 
is  the  effect  upon  a  boat  floating  from  a  river  into  the  ocean  ? 
5.  Why  is  it  easier  to  swim  in  salt  water  than  in  fresh  ? 


64 


INDUCTIVE  PHYSICS. 


SPECIFIC  GRAVITY— SINKING  OBJECT. 

Bxp.  91.  Bring  the  scales  to  a  perfect  balance  by 
means  of  the  wire  rider,  which  should  pinch  the  beam 
tightly  enough  to  be  held  firmly  in  place.  Hang  the 
rubber  stopper  to  the  hook,  and  balance  with  "Single  F" 


Exp.  97. 


shot.  Count  the  shot.  Bring  a  dish  of  water  up  under 
the  stopper  till  it  is  entirely  covered,  tip  and  shake  the 
stopper  to  get  all  the  air  out  of  the  holes,  then  remove 
shot  till  it  balances,  or  as  nearly  so  as  possible  with  that 
size  shot.  Count  the  shot  again. 

NOTE.  —  The  scales  are  delicate  enough  to  do  much  finer  work.  If 
this  is  desired,  ohtain  a  piece  of  sheet  lead,  and  cut  it  into  narrow  strips 
of  equal  width  throughout.  Balance  a  strip  with  "Single  F"  shot,  and 
cut  it  into  as  many  rectangular  pieces  as  it  equals  shot  in  weight.  Halve 
and  quarter  the  pieces,  and  give  each  pupil  a  piece  of  each  size.  It 
is  also  desirable  to  have  three  or  four  weights  each  five  or  ten  times 


SUPPLEMENTARY  GRAMMAR-SCHOOL    WORK.       65 

as  heavy  as  the  shot.  Strips  of  sheet  lead  easily  cut  with  a  knife  or 
scissors  to  the  desired  weight,  rolled,  flattened,  and  marked  v.  or  x.,  are 
the  neatest  and  easiest  made.  The  button-shaped  lead  dress-weights, 
or  even  bullets,  may  be  cut  down  to  "  ten-shot  weights."  New  nickel 
five-cent  pieces  may  be  used,  in  which  every  cent  equals  a  shot  in 
weight. 

INFERENCES.  1.  Which  is  the  heavier,  the  stopper  or  the 
same  bulk  of  water  ?  2.  •  What  is  their  relative  weight  as 
nearly  as  you  can  tell  from  this  experiment  ?  3.  Is  it  neces- 
sary to  balance  the  same  bulk  of  water  with  shot  ?  In  the 
same  way  experiment  with  various  substances,  such  as  glass, 
iron,  brass,  lead,  coal,  stone,  etc.,  and  make  a  table  showing 
the  weight  of  each  compared  with  water.  For  glass  use  a 
small  bottle  left  open  so  that  water  may  enter,  as  it  then  be- 
comes merely  a  piece  of  glass.  An  iron  nut  and  a  short  piece 
of  lead  pipe  are  usually  easily  obtained.  4.  Each  result  gives 
you  (very  nearly  at  least)  what  is  called  the  Specific  Gravity 
of  —  what  ?  5.  Is  it  of  the  object,  or  of  the  material  of  which 
the  object  is  made  ?  6.  Would  your  results  have  been  the 
same  had  you  used  larger  or  smaller  objects  of  the  same  ma- 
terial ?  If  you  are  not  sure,  ask  Nature.  7.  Does  Specific 
Gravity  mean  the  actual  weight  ?  8.  Do  you  have  to  know 
the  actual  weight  of  a  substance  either  in  air  or  in  water,  in 
order  to  find  its  Specific  Gravity  ?  9.  What  does  Specific 
Gravity  mean? 

SPECIFIC   GRAVITY  — FLOATING  OBJECT. 

Exp.  92.  Find  how  many  shot  it  takes  to  balance  the 
hard- wood  block.  Stick  a  pin  into  the  block,  and  by 
means  of  your  tin  dish  with  spout  find  its  bulk  of  water, 
and  then  balance  this  with  shot. 

INFERENCES.  1.  What  is  the  Specific  Gravity  of  the 
wood  ?  2.  If  the  Specific  Gravity  of  any  substance  is 


66 


INDUCTIVE  PHYSICS. 


greater  than  one,  what  will  it  do  when  placed  on  water,  and 
what  if  it  is  less  than  one? 

Bxp.  93.  Place  a  small  piece  of  soft-wood  board 
(base  of  scales  will  answer)  on  water,  and  determine  as 
nearly  as  you  can  by  looking  at  it  its  Specific  Gravity. 

INFERENCES.  1.  If  it  floats  with  just  one-half  above  the 
surface  of  the  water,  what  is  its  Specific  Gravity  ?  2.  What 
if  two-thirds  are  above  water  ?  3.  What  if  one-third  ? 

Bxp.  94.  Fill  apparatus  No.  5  of  first  course  with 
water.  Hold  it  upright  in  a  dish  to  catch  the  overflow. 
Lower  a  foot  rule  into  it,  and  by  see- 
ing how  much  it  projects  above  the 
water,  calculate  its  Specific  Gravity. 
Do  the  same  with  a  graphite  pencil, 
or  with  the  upright  piece  of  your 
scales. 

INFERENCES.     1.  What  is  the  Spe- 
cific Gravity  of  the  rule  ?      2.  What  of 
the  pencil  ?      3.  Does  this  experiment 
give    you  the   Specific  Gravity  of  the 
kind  of  wood  of  which  the 

9        pencil  is   made?      4.  What 

does    it   give   you  ?      5.    If 
you    should    perform    Ex  p. 
92  with  a  corked   bottle  of 
water  and   air,  of   what  would 
you   get,  the  Specific  Gravity? 

6.  Would  the  Specific  Gravity  of  all  bottles  of  water  and  air 
be  the  same  ?  7.  Would  it  be  the  same  for  all  pencils  made 
of  the  same  kind  of  wood  and  graphite  ?  8.  As  glass  is  a 
compound  of  many  substances,  used  in  many  different  pro- 
portions, would  you  expect  all  kinds  of  glass  to  have  exactly 
the  same  Specific  Gravity? 


Exp.  94, 


SUPPLEMENTARY  GRAMMAR-SCHOOL    WORK,       67 

Exp.  95.  First,  find  how  many  shot  will  balance  the 
small  bottle ;  second,  how  many  when  filled  with  water ; 
and  third,  how  many  when  filled  with  kerosene  oil ;  and 
find  the  Specific  Gravity  of  the  oil.  If  you  have  mercury 
enough,  find  its  Specific  Gravity  the  same  way,  and  see  if 
it  agrees  with  results  obtained  in  EXP.  83.  If  you  have 
not  enough  mercury,  choose  some  other  liquid,  such  as 
strong  brine,  which  you  can  easily  make  by  dissolving  in 
water  as  much  salt  as  possible. 

INFERENCE.    Give  the  Specific  Gravity  of  each. 

Exp.  96.  (If  convenient.)  Find  the  Specific  Gravity 
of  kerosene  oil  with  the  same  apparatus  used  with  water 
and  mercury  in  EXP.  83. 

INFERENCE.  How  nearly  does  it  agree  with  results  found 
in  EXP.  95  ? 

SPECIFIC    GRAVITY   OF   LIQUIDS    BY   BUOYANCY. 

Exp.  97.  With  your  balancing  apparatus  find  the 
Specific  Gravity  of  brine  and  of  oil,  or  of  alcohol,  by  find- 
ing the  buoyancy  of  each,  and  comparing  it  with  that  of 
water. 

INFERENCES.  1.  Give  the  Specific  Gravity  of  each,  and 
compare  with  that  found  by  the  other  method.  2.  Could  you 
find  the  Specific  Gravity  of  mercury  in  this  way  ?  3.  In 
general  of  what  liquids  could  you  ? 

SPECIFIC   GRAVITY   OF   LIGHT    SOLIDS   BY   MEANS   OF  A 
SINKER. 

Exp.  98.  With  your  balancing  apparatus,  and  by  work 
similar  to  that  which  you  have  already  done,  find  the  Spe- 


68  INDUCTIVE  PHYSICS. 

cific  Gravity  of  the  hard-wood  block  by  tying  to  it  a  piece 
of  lead  or  iron  sufficient  to  make  it  sink  in  water.  Make 
balancings  of  the  block  and  of  the  sinker  separately  and 
together,  both  in  air  and  as  far  as  possible  in  water.  Set 
down  the  value  of  each,  and  make  use  of  them  all  to  think 
with,  and  such  as  you  need  in  figuring  out  the  result.  Do 
all  the  thinking  necessary  yourself;  for,  if  you  are  told 
just  what  to  do,  you  might  as  well  not  use  this  method 
at  all. 

DENSITY. 

Thus  far  you  have  not  needed  to  do  any  weighing ; 
but  for  the  rest  of  the  experiments  you  must  know  the 
weight  of  your  shot,  or  at  least  know  how  much  water 
will  weigh  the  same  amount.  If  you  should  take  100 
"  Single  F  "  shot  and  just  water  enough  to  balance  them, 
and  measure  the  water  in  cubic  inches,  and  divide  by  100, 
you  would,  of  course,  get  the  amount  of  water  equal  in 
weight  to  one  shot.  This  we  have  done  for  you,  and 
found  that  a  cube  of  water  .4  of  an  inch  on .  each  edge 
equals  in  weight  a  "  Single  F  "  shot.  Now,  it  so  happens 
that  A  of  an  inch  (called  a  centimetre)  is  the  unit  of 
measurement  used  in  all  laboratories  and  for  all  scientific 
work,  both  in  Europe  and  America ;  and  the  weight  of  a 
cube  of  cold  water  of  that  size  is  the  unit  of  weight,  and  is 
called  a  gram.  This  much  of  the  Metric  System  you  need 
in  order  to  understand  the  subjects  that  follow.  Hence 
you  will  now  call  the  "Single  F"  shots  "gram  weights." 
You  will  also  familiarize  yourself  with  the  centimetre,  or 
unit  of  length.  Compare  it  with  the  inch,  then  compare 
30  cms.  with  the  foot.  Hereafter,  in  this  work  at  least, 


SUPPLEMENTARY  GRAMMAR-SCHOOL    WORK.       69 


make  all  your  measurements  in  centimetres  and  decimals 
of  the  centimetre.  As  you  will  find  it  more  convenient 
to  have  some  weights  heavier  than  one  gram,  obtain  some 
new  nickel  5-cent  pieces.  They  weigh  exactly  5  grams 
each.  Or  better,  make  some  5-  and  10-gram  weights  of 
sheet  lead,  or  of  something  else,  as  directed  in  note  to 
EXP.  91. 

NOTE.  — The  true  unit  of  the  Metric  System  is  the  metre,  which 
is  equal  to  39.37  inches  ;  but  just  as  we  divide  our  unit  of  value  — 
the  dollar  —  hy  100  to  get  a  smaller  unit,  which  we  call  a  cent,  so  the 
metre  is  divided  by  100,  and  the  smaller  unit  is  called  a  centimetre. 
This  is,  as  you  see,  not  quite  .4  inches ;  but  it  is  nearer  to  it  than  you 


can  possibly  measure  or 
a  microscope.  The  gram 
of  weight,  and  is  obtained 
metre  of  pure  water  at  the 
the  greatest  density,  which 
point. 


\ti 


even  distinguish  without 
is,  however,  the  true  unit 
by  taking  a  cubic  centi- 
temperature  when  it  has 
is  very  near  the  freezing 


etres 

lllllljj 


10    Centimet 

iiiilii  iiliiiiiiii  111  Minn  i 


11 iliii 


11 


1 1 1 


MINI 


Inches 
Fig.  11. 


Exp.  99.  Weigh  the  rectangular  block  of  wood. 
Measure  and  compute  its  cubic  contents.  The  weight  in 
grams  of  one  cubic  centimetre  is  called  the  density  of  the 
wood. 

INFERENCES.  1.  What  is  the  density  of  the  block  ? 
2.  How  does  density  differ  from  weight  ?  3.  How  does  the 
density  of  one  cubic  centimetre  of  anything  differ  from  its 
weight  ?  4.  What  is  the  density  of  cold  water  ?  5.  How 
does  density  differ  from  Specific  Gravity? 


70  INDUCTIVE  PHYSICS. 

Exp.  Auxiliary  to  99.  If  convenient,  obtain  some 
small  rectangular  blocks  of  different  kinds  of  wood,  and 
find  the  density  of  each. 

CUBIC   CONTENTS   BY  WEIGHING. 

Exp.  100.  Find  by  weighing,  both  in  air  and  in  water, 
the  number  of  cubic  centimetres  of  rubber  in  your  stop- 
per, also  of  glass  in  one  of  your  bottles,  and  of  stone  in 
some  small  irregular  piece ;  or  use  other  convenient 
objects. 

Exp.  101.  If  you  conquered  EXP.  98,  find  by  weigh- 
ing the  cubic  contents  of  a  piece  of  wood,  then  by  measur- 
ing, and  see  how  nearly  your  results  agree.  Invent  a 
bath-tub  by  means  of  which  you  could  (if  you  constructed 
it)  determine  your  exact  size  in  cubic  centimetres. 


AUXILIARY  APPARATUS  AND  EXPERIMENTS. 


Auxiliary  1.  This  apparatus  is  more  easily  made  with 
a  tin  tube  than  with  a  lamp  chimney.  Obtain  a  tube  of 
any  size  or  length ;  a  piece  of  speak- 
ing-tube about  12  inches  long  will 
answer.  Cork  the  lower  end,  and 
stick  it  in  a  hole  bored  in  a  block 
of  wood.  The  latter  serves  as  a 
stand.  "With  an  awl,  or  a  sharp  nail, 
punch  three  holes  equally  distant 
from  each  other,  as  in  the  illustra- 
tion. Enlarge  them  with  a  rat-tail 
file,  twisting  it,  and  pushing  the  edge 
of  the  tin  inwards,  so  as  to  make  a 
lip  or  "  burr."  Make  the  holes  equal 
in  size  to  those  in  the  "100  in  1 
Apparatus." 

For  showing  steady  side  pressure 
and  its  exact  law,  insert  the   U -tubes 
with  bends  each  half  full  of  mercury ; 
then  fill  the  tube  with  water,  and  ob- 
serve not  only  the  general  effect  upon  the  mercury,  but 
measure   the   amount  raised  in  each  tube,   and  compare 
with  corresponding  depths  of  water. 

NOTE.  -»  To  avoid  confining  the  air  in  the  tubes,  pour  in  water 
until  it  runs  into  first  tube,  then  carefully  pour  a  little  mercury  into 
71 


72 


INDUCTIVE  PHYSICS. 


tube  funnel.  Treat  the  second  tube  the  same  way,  then  pour  more 
mercury  into  first  if  necessary,  etc.  To  make  this  experiment  of 
some  aid  to  those  not  provided  with  the  apparatus,  we  have  violated 
our  general  rule,  which  is  to  show  the  apparatus  in  condition  for 
the  experiment,  and  not  during  it.  In  this  case,  we  have  shown  it 
in  progress,  as  the  pupil  should,  whenever  he  makes  a  drawing  to 
illustrate  an  experiment. 

CAUTION.  — When  handling  mercury,  be  careful  not  to  allow  it 
to  come  in  contact  with  a  gold  ring ;  for  the  two  metals  will  amal- 
gamate, giving  the  ring  the  appearance  of  silver.  Should  such  an 
accident  happen,  heating  the  ring  cautiously  will  drive  off  the  mercury, 
but  the  gold  will  need  reburnishing. 


Aux.  2.  Though  most  pupils  see  the  principle  in 
Exp.  16  without  extra  dishes,  better  have  two  additional 
pieces,  —  a  beer-bottle  and  a  lamp-chimney  or  tin  funnel, 
the  latter  corked,  and  standing  in  a  bottle.  Being  needed 
but  once,  and  for  only  half  a  minute,  one  set  will  do  for  a 
class  if  placed  where  the  pupils  can  use  it  in  turn ;  each 
using  his  own  pressure-gage  if  the  work  is  all  done  at 
school,  all  with  the  same  gage  if  regular  experiments  are 
done  at  home  and  only  the  auxiliaries  at  school.  A  very 
neat  funnel-dish  is  made  by  cutting  a  beer-bottle,  corking, 
and  standing  the  neck  part  inverted  in  the  lower. 


AUXILIARY  WORK.  73 

EASY  METHOD  OF  CUTTING  GLASS  BOTTLES. 

Bottles  are  easily  cut  with  a  fine  jet  of  burning-gas 
as  follows :  — 

Scratch  the  bottle  with  a  file  along  the  edge  of  a 
strip  of  paper,  tied  around  it  for  a  guide.  Remove  the 
paper,  and  rolling  the  bottle,  heat  it  along  the  scratch  to 
a  little  distance  ahead  before  the  crack  starts,  or  the  latter 
may  leave  the  mark.  With  thin  glass,  the  crack  will 
follow  the  gas-jet  quite  steadily  without  much  heating 


ahead ;  but  thick  glass  cracks  by  "  fits  and  starts."  After 
some  practice  you  can  dispense  with  the  scratch,  except 
an  inch  or  two  where  the  crack  is  to  be  started.  Sharp 
edges  are  smoothed  with  a  wet  file.  A  "  half-round  "  file, 
one  that  is  fiat  on  one  side  and  curved  on  the  other,  is 
best  for  this  purpose,  especially  for  the  inner  edge.  Thin 
bottles  may  be  cut  with  a  flat-wick  oil-lamp ;  but  the  line 
must  be  scratched  entirely  around,  and  even  then  the 
glass  will  not  always  crack  where  desired. 

With  little  practice,  bottles  may  be  cut  into  spirals 
from  end  to  end,  after  which  they  can  be  stretched  con- 
siderably without  breaking ;  when  released,  the  glass  will 


INDUCTIVE  PHYSICS. 


resume  its  original  length  with  a  sharp  click,  showing  its 
great  elasticity.  Test-tubes,  lamp-chimneys,  thin  glass 
tumblers,  and  beakers  are  very  easily  spiraled. 


The  latter  the  author  has  so  cut  as  to  be  stretched  to 
twice  their  original  length.  The  smaller  part  of  a  chim- 
ney, like  the  one  used  for  Aux.  1,  the  author  cut  into  a 
spiral  of  60  coils  within  a  length  of  8  inches.  The  diam- 
eter of  the  chimney  was  1]  inches.  If  you  can  estimate 
the  present  length  of  that  8-inch  piece  of  glass,  you  will 
find  that  it  is  more  than  three  times  that  of  your  height. 


To  break  the  tubing  squarely,  scratch  it  with  the  file, 
then  hold  it  with  the  thumbs  opposite  the  scratch,  and 
break  as  you  would  a  twig.  The  sharp  edges  are  easily 
removed  by  means  of  a  file;  they  may  also  l>e  melted 
smooth  in  the  Bunsen  burner.  To  close  the  end,  or  to 
partly  close  it  so  that  it  may  be  used  as  a  jet,  hold  it 


AUXILIARY   WORK. 


75 


in  the  hottest  part  of  the  Bunsen  blaze,  and  keep  turn- 
ing it  till  the  hole  is  small  enough.  To  bend  it,  use  a 
common  gas-jet,  not  very  large,  and  turn  it  while  heating. 


A  little  practice  will  enable  you  to  do  it  neatly.  The  cut 
below  shows  how  to  make  a  small  funnel  from  a  glass 
tube,  by  using  the  Bunsen  burner  and  a  piece  of  charcoal 
sharpened  like  a  pencil. 


If   not  supplied  with   gas,  you  can  shape  thin  glass 
tubing  with  an  alcohol  or  a  common  flat^wick  oil-lamp ;  but 


76  INDUCTIVE  PHYSICS. 

it  is  very  difficult  work.  Skilful  glass-blowers  can  work 
with  crude  apparatus  and  poor  materials,  but  pupils  not 
accustomed  to  the  manipulation  of  glass  require  the  best 
of  appliances.  Do  not  try  to  hurry  your  work.  When 
the  glass  begins  to  yield  under  the  action  of  the  heat, 
do  not  bend  or  shape  it  too  rapidly.  Unless  necessary,  do 
not  bend  a  tube  at  too  sharp  an  angle.  In  the  above  cut, 
the  tube  is  bent  at  a  sharper  angle  than  is  usually  desired. 


Aux.  3. 


Aux.  3  shows  a  water-level  made  of  two  small  bottles 
with  their  bottoms  cut  off,  two  corks,  and  a  piece  of  glass 
tubing ;  it  shows  also  how  the  level  is  mounted  upon  a 
tripod  stand,  and  is  used  for  getting  the  difference  in 
level  —  or  height  above  the  sea  —  between  two  places. 

Aux.  4.  A  fine  auxiliary  to  Exp.  19  may  be  per- 
formed by  placing  a  large  tin  can  or  pail  on  a  high  shelf 
near  an  open  window,  out  of  which  the  fountain  can 
play.  (To  make  a  hole,  see  Aux.  l.)  If  not  well  sup- 
plied with  rubber  tubing,  connect  two  from  pupils'  sets 
by  means  of  a  short  glass  tube,  and  insert  the  elbow  jet- 


AUXILIARY   WORK. 


11 


tube,  held  in  position  by  two  blocks ;  or  make  one  that 
will  stand  alone  by  bending  a  long  piece  of  tubing  twice, 
each  elbow  being  at  right  angles  to  the  other.  (See  stand 
for  gas-jet  in  glass-bending  picture  above.) 


Auxs.  4  and  5. 

If  you  have  gas,  a  great  many  pieces  of  very  valu- 
able apparatus  may  be  easily  made  of  soft  glass  tubing 
obtained  at  drug-stores,  or  purchased  by  the  pound  of 
school-supply  dealers.  Do  not  get  the  cheap,  thin  tubing ; 
it  breaks  easily,  and  is  very  difficult  to  work.  The  only 
tools  absolutely  needed  are  a  three-cornered  file,  a  com- 


78  INDUCTIVE  PHYSICS. 

mon  gas  flame,  and  a  Bunsen  burner,  or  the  recently  in- 
vented Bunsen  blast  alcohol  lamp,  sold  by  the  L.  E.  Knott 
App.  Company  of  Boston,  and  Eimer  &  Amend  of  New 
York. 

Aux.  5.  (See  cut  above.)  Exps.  20  and  21  are 
very  pretty  performed  with  a  tall  bottle.  A  quart  ink- 
or  wine-bottle  does  very  well ;  a  hole  is  much  more  easily 
made  with  a  file  in  the  edge  than  in  the  side  of  a  bottle, 
and  does  just  as  well  for  these  experiments.  Still  better 
and  cheaper  is  a  tin  tube  a  foot  or  more  long,  corked  at  the 
bottom,  and  provided  with  a  wire  bail.  Make  the  holes 
just  above  the  cork,  and  insert  tubes  from  the  pupils'  sets. 
If  the  class  is  large,  it  is  better  to  have  a  piece  for  each 
experiment,  and  but  one  piece  in  a  window,  to  which 
pupils  go  in  turn  to  inspect  it.  Exp.  21  may  be  done 
in  a  variety  of  ways,  thus :  with  both  tubes  horizon- 
tal in  a  large  tin  pan  to  catch  the  water ;  with  the  pan 
nearly  full  of  water,  the  tubes  submerged ;  with  one  tube 
horizontal,  the  other  at  any  angle ;  with  both  tubes  at  dif- 
ferent angles,  imitating  a  lawn  fountain. 

No  other  auxiliary  apparatus  is  worth  so  much  in 
proportion  to  its  cost  as  this  ;  while  performing  Exp.  21, 
Aux.  apparatus  4  may  be  combined  with  Aux.  appara- 
tus 5  by  holding  its  jet-tul>e  so  that  it  will  play  into  the 
top  of  it,  thus  prolonging  the  experiment. 

Aux.  6.  Procure  a  three  or  four  quart  hot-water  bag.1 
Attach  to  it  several  feet  of  rubber  tubing  by  means  of  a 

1  A  two-quart  bag  costs  from  eighty  cents  to  one  dollar,  according  to 
the  quality.  A  three-quart  bag,  which  is  a  much  better  size  for  the  experi- 
ment, costs  about  twenty-five  cents  more. 


AUXILIARY   WORK. 


79 


perforated  cork  and  a  short  piece  of  glass  tube.  Place 
the  bag  upon  the  floor  with  a  piece  of  board  over  it,  on 
which  stand,  or  place  heavy  weights ;  then  pour  water  into 
the  funnel  at  the  end  of  the  tube. 


NOTE.  —  To  make  a  funnel :  if  gas  is  available  with  which  to  cut 
glass,  use  the  top  of  a  bottle.  With  a  rat-tail  file  make  a  hole  in  a  cork 
that  fits  tightly,  and  insert  one  of  the  short  glass  tubes.  Or  take  the 
pressed  tin  cover  of  a  baking-powder  can,  and  make  a  hole  in  the  centre 
(see  Aux.  1),  pushing  the  tin  outward,  and  fit  glass  tube  to  it  with  a 
a  short  piece  of  rubber  tube. 


80 


INDUCTIVE  PHYSICS. 


Aux.  7.  A  fine  auxiliary  piece  may  be  made  by  tying 
sheet  rubber  over  the  large  end  of  a  lamp-chimney.  Fill 
the  latter  with  water,  and  insert  the  stopper  or  a  cork 
with  tubes,  as  illustrated,  and  press  on  the  rubber. 


Aux.  8.  (Study  this  figure,  if  not  provided  with  the 
apparatus.)  Connect  a  tube  with  piston  to  two  others  of 
the  same  size,  as  illustrated.  With  the  water  at  equal 
depth  in  each,  insert  the  piston  in  the  middle  one,  and 
transfer  the  water  to  the  other  two. 

INFERENCE.  How  much  pressure  on  the  surface  of  the 
water  in  each  will  balance  one  unit  on  the  surface  of  water  in 
middle  tube  ?  Does  the  amount  of  pressure  transferred  to 
each  side  tube  bear  the  same  relation  to  that  on  the  piston, 
as  the  amount  of  water  transferred  bears  to  that  at  first  in 
the  middle  tube  ?  What  things  are  in  the  same  relation  to 
each  other  as  applied  and  transmitted  pressure  ?  Did  you 
make  them  so  in  inferences  to  Exp.  29  ? 


AUXILIARY   WORK. 


81 


Aux.  9.  The  rubber  bulb  of  an  atomizer,  found  at 
drug  or  rubber  stores,  makes  a  valuable  addition  to  your 
apparatus,  increasing  the  beauty  and  instructiveness  of 
several  experiments  in  air.  Attach  it  to  the  rubber  tube 
in  Exp.  34,  and  it  represents  the  pump  on  the  deck  of 
a  wrecking-vessel,  pumping  air  down  to  the  workmen  in  a 
diving-bell. 

Aux.  1O.  Even  if  you  are  not  provided  with  an  air- 
pump  and  delicate  scales,  it  is  not  necessary  to  take  for 


Aux.   70. 

granted  that  air  has  weight.  If  you  know  how  to  suck, 
the  following  apparatus  will  show  it  clearly ;  and  if 
you  do  not,  you  should  practise  until  you  do,  for  kind 
Nature  has  given  you  a  pump  good  enough  for  any 
necessary  experiment  with  air,  even  that  of  finding  its 
exact  weight  if  you  are  provided  with  delicate  scales. 

Suspend  in  the  window  a  metre  rod  or  yard-stick  by 
a  screw-hook  or  eye,  in  the  centre.  Drive  a  tack  into 
each  end,  on  which  hang  quart  or  larger  bottles,  one  being 


82  INDUCTIVE  PHYSICS. 

tightly  fitted  with  a  stopper,  glass  tube,  and  rubber  tube 
with  plug  in  end.  Then  pour  shot,  sand,  or  water  into 
the  open  bottle  until  it  balances  the  other,  with  bottoms 
just  above  the  window-sill.  A  wire  rider  easily  slid  along 
the  stick  will  enable  you  to  get  an  exact  balance.  Suck 
all  the  air  you  can  from  the  plugged  bottle,  resting  several 
times,  and  replace  plug. 

INFERENCE.    Why  does  the   other  bottle  now  rest  upon 
the  window-sill  ? 


Aux.  11.  Place  a  strip  of  thin  board  about  two  feet 
long  on  the  table,  with  half  its  length  projecting  over  the 
edge.  Over  the  portion  on  the  table  lay  smoothly  several 
thicknesses  of  newspaper,  full-page  size.  Strike  the  pro- 
jecting end  as  hard  a  blow  as  you  can ;  and  if  the  blow  is 
not  followed  by  a  push,  you  cannot  knock  the  board  off 
the  table. 

INFERENCE, 


AUXILIARY    WORK. 


Aux.  12.  Half  fill  the  larger  test-tube  with  water, 
and  place  the  smaller  one  in  it,  the  bottom  touching 
the  water.  Taking  hold  of  the  larger  one,  invert  them. 
If  they  are  of  correct  relative  size,  the  smaller  will  not 
fall  out,  but  will  rise  inside  the  larger  to  the  top. 

INFERENCE.    Why  ? 


Aux.  13.  A  fine  "  suction  " 
or  lifting  pump  is  easily  made 
with  a  straight  lamp-chimney. 
A  marble  and  a  large  shot 
make  the  best  and  most  inter- 
esting as  well  as  the  cheapest 
valves.  The  shot  will  rise  an 

AUX.    1 3. 

inch    or    two    with    the    water 

when  the  piston  is  pushed  rapidly  down,  and  fall  back, 
perhaps  not  over  the  hole ;  but  when  the  piston  starts 
upward,  it  gets  into  place  instantly,  making  a  very 
interesting  experiment  in  itself.  The  piston  should  be 


84  INDUCTIVE  PHYSICS. 

made  of  a  rubber  stopper  with  two  holes,  and  should 
work  very  loosely,  —  in  fact,  it  should  not  pump  water 
without  first  being  primed;  then  it  works  so  easily  that 
there  is  no  danger  of  breaking  anything.  If  made  of 
wood,  the  piston-rod  is  easily  pinned  into  one  hole  of  the 
stopper;  if  of  glass  rod,  heat  it  in  the  Bunsen  lamp  till 
soft,  then  crowd  the  ends  to  produce  the  bulge  which 
keeps  the  stopper  from  slipping  up ;  and  by  heating  the 
end,  and  pressing  it  against  something  hard,  a  knob  is 
made  upon  the  end  which  can  be  forced  easily  through 
the  hole  in  rubber  stopper.  Treat  the  upper  end  in  the 
same  way,  and  insert  the  piston  from  below.  It  should  go 
in  tightly  at  the  end,  which  is  generally  a  little  smaller 
than  the  rest  of  the  chimney.  The  lower  stopper  may  be 
either  rubber  or  cork,  and  the  tube  should  not  reach  quite 
through  it.  If  cork  is  used,  make  the  hole  from  the  small 
end  so  that  its  edges  may  not  be  torn,  in  which  case  the 
valve  is  imperfect.  If  you  are  not  an  expert  in  digging 
holes  in  glass,  though  it  is  easily  done,  the  spout  may  be 
omitted,  and  the  water  allowed  to  run  over  the  top.  With 
the  spout,  however,  the  experiment  is  much  more  striking. 
Fill  the  Apparatus,  or  a  bottle,  with  water,  insert  the 
pump-tube  through  the  stopper,  and  plug  the  other  holes. 
Work  the  piston  up  and  down. 

INFERENCES.  1.  What  happens  ?  2.  Why  do  you  not 
pump  water  now?  3.  Remove  one  plug  from  the  stopper, 
work  the  piston-rod,  and  explain  every  step  of  the  experi- 
ment. 4.  Could  you  pump  water  from  any  cistern  that  was 
air-tight?  5.  Is  it  proper  to  say  that  the  water  is  "sucked 
up,"  or  to  call  a  pump  a  "  suction "  pump  ?  6.  What  forces 
it  up  ?  7.  What  produces  the  necessary  conditions  ? 


AUXILIARY  WORK. 


85 


Aux.  14.  A  lamp-chimney  makes  a  fine  piece  of  "  how 
we  breathe  "  apparatus,  and,  with  a  long  jet-tube,  can  be 
used  for  a  "  vacuum  fountain." 

Aux.  15.  Fasten  the  long  rubber  tube  to 
a  hot>  water  bag  (see  Aux.  6),  place  weights 
of  50  or  100  pounds  upon  the  bag,  and  blow 
through  the  tube.  If  the  bag  is  large  enough, 
you  can  sit  upon  it,  and  raise  yourself  with 
your  own  breath.  For  raising  a  large  diction- 
ary, or  even  a  stack  of  them,  a  tight  paper 
bag  will  answer;  but  it  is  very  difficult  to  get 
it  fastened  air-tight  around  the  tube.  To  do 
so,  connect  them  by  means  of  the  Apparatus, 
around  open  end  of  which  the  mouth  of  bag  is  tightly 
fastened. 

This  experiment  is  sometimes  published  as  a  trick,  and 
is  called  "  The  Power  of  the  Breath."  But  the  "  power 


of  the  breath  "  is  only  about  an  ounce.  With  a  properly 
constructed  apparatus,  however,  a  man  can,  with  his  breath, 
lift  an  ox.  Compare  this  principle  with  that  of  the  water- 
press,  Exp.  30. 


36  INDUCTIVE  PHYSICS. 

Aux.  16.  Place  a  large  sponge  in  a  plate  half  filled 
with  water.  Note  what  takes  place.  With  a  few  drops 
of  ink  or  bluing,  color  a  little  water  in  a  shallow  dish,  and 
stand  a  lump  of  sugar  in  it.  Note  the  effect.  Stand  a 
piece  of  cane,  rattan,  or  blackboard  crayon,  in  a  little  tur- 
pentine or  kerosene  oil,  and  after  an  hour  or  two,  accord- 
ing to  the  length  of  the  piece  used,  hold  a  lighted  match 
to  the  upper  end. 

INFERENCE.  Explain  the  use  of  blotting-paper,  candle- 
and  lamp-wicks;  and  mention  any  othei-  similar  cases  you 
can  think  of. 


Aux.  17.  The  diagrams  above  represent  a  simple  form 
of  the  air-pump,  used  to  suck  or  "exhaust"  a  part  of  the 
air  from  a  bottle.  C  is  a  cylinder  in  which  works  the 
piston  P ;  v,  v,  are  valves,  or  little  doors,  opening  one 
way  only. 

INFERENCES.  1.  Explain  its  action.  When  the  piston  is 
being  pushed  in,  are  the  valves  open  or  shut?  Are  they  open 
or  closed  when  the  piston  is  being  pulled  out  ?  Tell  about 
each  one  in  each  case.  2.  Does  the  force  applied  by  the  hand 
open  the  valves  ?  What  forces  the  air  out  of  the  bottle  when 
the  lower  valve  is  open,  and  what  opens  it  ? 

A  mercury  air-pump  may  be  constructed  with  parts  of 
three  pupils'  sets  of  apparatus.  With  this  pump,  nearly  all 


AUXILIARY   WORK.  87 

the  air  may  be  taken  from  a  bottle.  The  apparatus  itself 
is  very  cheap ;  but  its  use  requires  considerable  mercury 
(none  of  which  need  be  wasted,  however),  time,  and  atten- 
tion. It  is  well  worth  constructing,  if  only  for  the  purpose 
of  studying  its  operation.  If  provided  with  a  retort-stand 


and  a  glass  funnel,  they  may  be  used  instead  of  Apparatus 
a  and  its  supporting  blocks.  A  screw-clamp  for  regulating 
the  flow  of  mercury  is  better  than  the  clothespin.  In  place 
of  Apparatus  i,  one  may  use  a  small  inverted  bottle  with 
the  bottom  cut  off.  A  single  tube  (represented  as  broken) 
reaches  from  b  to  c.  If  the  pump  is  used  for  practical  pur- 
poses, and  a  nearly  perfect  vacuum  is  desired,  this  tube 


88  INDUCTIVE  PHYSICS. 

should  be  about  two  and  a  half  feet  long,  with  a  thicker 
wall  and  smaller  hole  than  those  commonly  used.  If  used 
only  for  the  purpose  of  study,  two  or  three  pieces  well  con- 
nected with  short  pieces  of  rubber  tubing  will  answer  very 
well.  If  a  small  amount  of  mercury  is  used,  the  experi- 
menter is  kept  busy  pouring  it  back  into  a.  Two  tumblers 
should  be  used  ;  then,  by  tipping  c  a  little  to  empty  it,  time 
enough  during  which  there  is  no  flow  from  it  is  obtained 
in  which  to  change  dishes.  If  the  glass  tubes  between  b 
and  d  do  not  nearly  or  quite  touch  each  other,  the  rubber 
tube  will  be  compressed  (as  shown  in  picture)  so  much  as 
to  prevent  getting  a  free  flow  of  the  air  from  d.  If  they 
do  touch,  by  keeping  the  rubber  attached  to  c7,  with  a 
little  care  they  can  be  disconnected  without  allowing  any 
air  to  enter.  In  order  to  secure  the  largest  number  of 
observations,  tube  e,  in  which  they  are  made,  should  be 
a  long  one. 

Aux.  18.  With  Exp.  74  use  the  atomizer  bulb.  It 
will  throw  a  stream  of  water  to  a  considerable  distance,  — 
fifteen  or  twenty  feet. 

Aux.  19  illustrates  the  principle  of  the  force-pump 
and  the  fire-engine.  The  piston  must  fit  closely;  hence 
the  one  used  in  the  lifting-pump,  the  hole  plugged,  will 
not  answer.  The  slit-tube  valve  was  used  in  "  How  we 
pump  water,"  Exp.  45.  The  larger  the  bottle  used  for 
the  air  and  water  chamber,  the  better. 

INFERENCKS.  1.  Explain  its  operation.  2.  Why  is  a  large 
bottle  better  for  an  air  chamber  than  a  small  one  ?  3.  Why 
do  you  get  a  continuous  stream  ?  4.  Is  the  discharge  into 
the  bottle  continuous? 


AUXILIARY   WORK. 


89 


Aux.   19. 

Aux.  2O.  Use  an  atomizer  bulb,  and,  with  the  stopper 
wet  and  tightly  inserted,  pump  air  into  the  bottle  until 
the  stopper  flies  out.  It  will  be  expelled  with  consider- 
able force,  perhaps  to  the  height  of  the 
ceiling.  Observe  the  cloud  of  mist  that  fre- 
quently appears  within  the  bottle  after  the 
explosion.  If  it  does  not  appear  at  first,  try 
it  again  on  succeeding  days  to  see  if  you  can 
learn  the  condition  of  the  atmosphere  neces- 
sary to  produce  it;  keep  your  record  for 
future  use. 

Aux.  21.  Get  a  tall  bottle  of  any  shape  ; 
fit  a  cork  to  it;  fill  it  with  water,  and, 
after  the  small  vial  has  been  inserted,  cork 
it.  The  small  bottle  is  a  "diver."  If  the 
latter  contain  just  enough  water,  on  tight- 
ening the  cork  a  very  little  it  will  go 
down ;  on  loosening  the  cork  it  will  come 
up.  If  desired,  a  small  image  may  be  cut  out  of 


90 


INDUCTIVE  PHYSICS. 


tin,  or  any  sheet  metal,  and  hung  to  the  neck  of  diver, 
making  a  water-balloon.  To  transfer  the  diver  to  the 
large  bottle  with  small  mouth,  fill  the  bottle,  then,  after 
the  proper  amount  of  water  in  the  vial  has  been  found 
by  experiment,  place  a  bit  of  paper  under  the  mouth 

of  the  diver  and  easily 
transfer  it;  then  remove 
the  paper.  With  care 
and  a  steady  hand  you 
can  remove  it  without 
the  paper,  and  without 
losing  any  water  from  it. 
(The  bottle  diver  will  be 
used  again  in  studying 
the  effect  of  heat  on 
fluids.) 

Aux.  22.  As  this  ex- 
periment requires  parts  of 
apparatus  from  two  sets, 
and  assistance  in  starting 
it,  two  pupils  had  bet- 
ter work  together.  One 
should  hold  the  funnel 
and  bottle  full  of  water 
as  illustrated,  the  other 
pours  water  into  the  funnel  to  start  it. 
INFERENCE. 

Aux.  23.  Arrange  three  Apparatuses  as  illustrated, 
and  blow  through  the  open  bent  tube  to  start  it.  Vary 
the  height  of  the  fountain-piece,  and  notice  the  effect 


AUXILIARY   WORK. 


91 


upon  the   fountain.     Try  the  same  with  the 
head,"  the  bottle  in  which  you  blew. 


fountain- 


INFEBENCE.  Explain  each  step  of  the  experiment,  and 
be  sure  to  tell  what  variations  affect  the  height  to  which 
water  rises,  and  what  the  length  of  stream  after  the  water 
leaves  the  jet-tube. 

Aux.  24.  This  is  a  very  striking  and  easily  made 
form  of  Hero's  Fountain,  in  which  a  jet  of  water  rises 


92  INDUCTIVE  PHYSICS. 

higher  than  its  source.  The  upper  part  is  the  top  of  a 
large  bottle ;  the  central  piece  is  the  longer  part  of  a 
lamp-chimney,  like  the  one  used  in  Aux.  1 ;  the  lower 
part  is  the  Apparatus.  The  lamp-chimney  is  easily  cut 
at  the  narrow  place  by  the  aid  of  a  triangular  file  and  the 
gas  glass-cutter.  All  the  glass  tubes  are  open  at  both 
ends  ;  c  being  a  jet-tube  passing  through  the  upper  stopper, 
and  nearly  reaching  the  lower.  Two  corks  —  or,  better, 
rubber  stoppers  —  may  be  used  where  one  is  illustrated, 
if  the  same  one  does  not  fit  both  glass  pieces  tightly 
enough.  For  the  bottom  piece,  a  large,  heavy  bottle  is 
preferable  to  the  Apparatus.  This  apparatus  may  be 
made  with  one  piece  less  of  glass,  by  using  the  long  neck 
and  a  part  of  the  body  of  a  wine-bottle,  together  with  two 
rubber  stoppers,  thus  dispensing  with  the  lamp-chimney; 
made  in  this  manner,  however,  it  is  a  short-lived  fountain, 
the  reservoir  being  much  too  small.  Of  course,  if  well 
made,  this  apparatus  never  needs  taking  apart;  for,  by 
inverting  it,  the  reservoir  is  filled,  and  the  surplus  of 
water  in  the  bottle  is  discharged,  through  the  jet^tube.  If 
the  tubes  do  not  discharge  freely,  a  little  careful  shaking 
of  the  apparatus  will  make  them  do  so. 

INFERENCE.  Explain  every  step,  both  of  the  working  of 
the  fountain  and  the  process  of  refilling  the  reservoir. 

Aux.  25.  This  is  an  intermittent  fountain,  in  which 
the  water  rises  in  spurts  higher  than  its  source,  some  of  it 
passing  several  times  from  one  bottle  to  the  other  before 
the  action  finally  ceases.  If  the  apparatus  be  carefully 
constructed,  the  water  strikes  the  bottom  of  the  upper 
bottle  with  considerable  force  at  each  throw.  The  foun- 


AUXILIARY  WORK.  93 

tain  never  requires  readjusting ;  and  to  prepare  it  for  a 
second  period  of  activity,  it  is  necessary  only  to  invert 
the  apparatus  until  water  runs  into  the  lower  bottle,  as 
shown   in   the   illustration.      It    may    be    con- 
structed of  two  Apparatuses,  or,  better,  of  two 
large  bottles,  one  or  two  corks  or  rubber  stop- 
pers, and  two  jet-tubes,  the  bent  one  having  a 
smaller  opening    than    the    other.       The  small 
funnel   at  the   upper   end  of  the  straight  tube 
is  not  a  necessity,  but  it  is  easier  to  construct 
it  thus  (see   "Auxiliary  Work,"  p.  75)  than 
to  get  the  tubes  accurately  enough  aligned  to 
work  well  without. 

INFERENCES.  1.  Explain  the  condition  of  the  air  in  each 
bottle  before  action  begins.  2.  What  force  produces  the  first 
change  in  atmospheric  conditions,  and  what  is  the  change  ? 
3.  What  other  force  comes  into  play,  and  what  are  its  results, 
both  visible  and  invisible  ?  4.  Explain  what  occurs  and  why, 
when  the  apparatus  is  inverted. 

Aux.  26.  This  is  an  intermittent  fountain  made  of 
an  ordinarily  shaped  quart  bottle,  the  top  of  another  used 
simply  as  a  stand  for  the  first,  the  bottom  of  a  larger 
bottle,  a  glass  fruit-jar,  and  pieces  of  tubing  and  corks. 
For  greater  stability,  the  apparatus-tube  c,  which  is  bev- 
elled at  both  ends,  should  touch  the  dish  at  its  lower,  and 
the  cork  at  its  upper  end.  It  need  not  be  so  long  as 
shown  in  the  cut;  it  would  better  be  short  enough  to 
allow  the  bottle  to  rest  upon  its  stand,  into  which  it  is 
firmly  fitted  with  a  cork.  Tube  a  is  the  one  that  fur- 
nishes the  intermittent  stream,  and  if  the  apparatus  be 


94 


INDUCTIVE  PHYSICS. 


adjusted  with  care,  another  tube  like  it  may  be  fitted  to 
the  opposite  side  of  the  bottle.  Without  very  careful 
adjustment,  however,  air  will  enter  one  tube,  and  thus 
prevent  an  intermittent  flow  from  either; 
hence  you  would  better  make  the  fountain 
with  a  single  tube  at  first,  then  add  the 
second  if  desired.  A  cap  is  placed  upon 
this  tube  while  the  bottle  is  being  filled 
and  corked.  Tube  £,  leading  from  the  large 
dish  to  the  jar  below,  furnishes  a  steady 
stream,  and  lias  a  smaller  opening  than 
a ;  if  small  enough,  the  fountain  will  run 
for  an  hour  or  more,  intermitting  perhaps 
every  other  minute.  If  the  holes  in  the 
bottles  used  must  be  drilled,  have  the  one 
in  this  dish  at  or  near  the  centre;  but  if 
you  make  them  with  files,  the  easiest  way 
is  to  make  the  hole  in  this  dish  at  the 
edge  like  the  one  for  tube  a,  and  make 
b  with  a  double  bend  leading  into  the 
jar  through  a  notch  filed  in  the  edge  of 
its  mouth.  If  large,  stand  may  also  need 
notching. 


AUK.  27.  This  might  be  called  a  fountain  sponge. 
The  principle  of  its  action  is  the  same  as  that  of  the  com- 
mon fountain  ink-well.  The  lower  halves  of  two  bottles 
are  connected  by  a  short  piece  of  tubing.  In  one  of  the 
bottle-bottoms  is  placed  the  sponge;  the  other  is  placed 
like  a  cap  over  the  mouth  of  a  bottle  filled  with  water, 
which  is  then  inverted.  The  sponge  keeps  moist  for 


AUXILIARY    WORK. 


95 


weeks  or  months,  according  to  size  of  bottle  and  condition 
of  the  atmosphere.  The  water  escapes  only  by  evapora- 
tion from  the  sponge,  if  the  latter  is  not  removed  from  its 
dish.  It  may  be  used  as  a  penwiper,  or  for  moistening 
the  gummed  surfaces  of  stamps  and  envelopes. 


Aux.  28.  This  is  a  student-lamp,  the  operation  of 
which  is  easily  studied,  as,  with  the  exception  of  a  cork 
and  two  nails,  it  is  made  entirely  of  glass.  The  cork 
tightly  fits  the  inverted  half  bottle,  and  is  perforated 
for  a  tube  through  which  the  oil  reaches  the  wick.  Two 
nails  are  driven  into  the  cork,  and,  with  the  tube,  form 
the  support  for  the  lamp.  The  chimney  rests  on  the  tube 
and  two  bits  of  wood,  which  are  separated  just  enough  to 
allow  sufficient  draft,  the  latter  being  easily  adjusted  by 
experiment.  This  piece,  which  is  easily  made,  furnishes 
also  a  valuable  auxiliary  experiment  in  the  study  of  com- 
bustion. 


96  INDUCTIVE  PHYSICS. 

Aux.  29.  This  is  an  easily  made  and  a  very  service- 
able force-pump  for  use  with  either  liquids  or  gases.  With 
a  single  piece  of  rubber  tubing  in  place  of  the  long  sec- 
tional one  shown  in  the  picture,  it  may  be  used  for  pump- 
ing air  wherever  in  previous  lessons  the  "  atomizer  bulb  " 
is  recommended.  It  works  equally  well  in  pumping  or 
forcing  a  stream  of  water.  The  rubber  bulb,  which  con- 
tains no  valve,  should  be  as  heavy  and  elastic  as  possible. 
One  end  of  a  bent  tube  is  fitted  tightly  into  it  by  means  of 
a  piece  of  rubber  tubing,  the  other  end  passes  through  a 


Aux,  29. 

stopper  containing  two  holes  into  one  of  the  small  bottles. 
The  bottles  are  connected  by  a  piece  of  glass  tubing  which 
has  upon  one  end  a  valve  like  those  in  the  apparatus  for 
pumping  water  (Exp.  45).  A  similar  valve  is  placed  upon 
the  end  of  the  tube  passing  through  the  edge  of  the  other 
bottle.  The  holes  in  the  bottles  may  be  drilled  each  in  the 
centre  of  the  bottom;  if  done  with  a  file  they  are  more 
easily  made  in  the  edges.  Glass  tubes  are  fastened  in 
tightly  with  bits  of  rubber  tubing.  The  glass  tube  with 
the  valve  on  the  end  should  be  longer  than  the  bottle.  It 
is  first  inserted  through  the  neck ;  then,  if  desired,  it  may 
.be  shortened.  The  long  tube  shown  in  the  picture  is  made 
of  rubber,  glass  tubes,  and  a  short  piece  of  rattan.  The 


AUXILIARY   WORK.  97 

glass  tube  in  the  outer  end  is  a  jet^tube ;  each  of  the  other 
two  has  a  small  notch  filed  in  it,  and  is  of  such  size  as  to 
allow  the  rubber  tube  to  slide  over  the  notch  to  prevent 
leakage.  The  piece  of  rattan  also  has  a  small  notch  cut  in 
it.  A  glass  tube  bent  at  a  sharp  angle,  inserted  in  the  end 
of  a  rubber  tube  and  hung  upon  the  edge  of  the  tumbler, 
keeps  in  place  better  than  rubber  tubing. 

To  study  the  operation  of  this  pump,  use  it  first  with 
water,  without  the  long  delivery,  having  in  its  place  a 
short  rubber  tube  hanging  in  a  dish  to  catch  the  water. 
With  the  hand,  alternately  compress  and  release  the  bulb ; 
note  what  happens.  By  experiment  find  how  to  hold  the 
pump  to  deliver  a  stream  of  water,  and  retain  considerable 
air  in  each  bottle ;  how  to  retain  air  in  one  bottle  only ; 
and  how  to  fill  both  with  water.  Explain  the  working  of 
the  pump,  naming  each  force  in  order,  beginning  with  the 
force  that  compresses  the  bulb.  Be  particularly  careful 
about  the  second  and  third  forces,  for  very  likely  you  will 
overlook  one  of  them.  Does  the  pump  act  differently 
with  air  than  with  water?  Try  each,  and  devise  your 
own  means  for  determining  whether  there  is  any  difference 
in  principle.  The  apparatus  with  delivery  tube,  shown 
in  the  picture,  is  used  to  illustrate  the  circulation  of  blood. 
The  pump  represents  the  heart;  the  tube,  between  the 
pump  and  the  rattan,  an  artery;  the  rattan,  the  capil- 
laries ;  the  tube  beyond,  which  should  rest  in  the  tumbler 
of  water,  represents  a  vein. 

Every  time  you  squeeze  the  bulb,  the  water  spurting 
from  the  notch  in  the  glass  tube  at  the  right  of  the  rattan 
illustrates  the  manner  in  which  one  loses  blood  when  an 
artery  is  severed.  Slip  the  rubber  tube  over  that  hole 


INDUCTIVE  PHYSICS. 


and  work  the  pump;  the  slow  but  steady  leaking  from 
the  rattan  and  the  other  glass  notch  illustrates  how  a 
wound  bleeds  when  capillaries  or  a  vein  is  cut.  With 
the  tube  lying  on  the  table  while  working  the  pump,  press 
upon  the  tube,  or  bend  it  sharply  beyond  the  rattan ;  the 
extra  spurt  of  water  from  the  jet-tube  illustrates  one  way 
in  which  the  circulation  of  blood  is  increased  by  exercise. 


0 


Aux.  3O.  Cut  and  bend  a  piece  of  heavy  writing- 
paper  or  light  cardboard  as  illustrated,  and  balance  it  on 
the  point  of  a  long  needle.  A  large  flat  cork  or  any 
corked  bottle  makes  a  good  stand  for  the  needle.  Fan 
one  end  with  a  piece  of  cardboard  or  with  the  hand, 
moving  it  from  the  centre  outward,  and  the  paper  will 
swing  towards  the  fan. 

INFERENCE. 

Aux.  31.  Insert  a  glass  tube  tightly  into  a  hole  in  a 
piece  of  thick  cardboard.  Insert  a  pin  to  its  head  in  the 
centre  of  a  piece  of  thin  cardboard  of  about  the  same  size. 
Place  the  former  over  the  latter  as  illustrated ;  while 
blowing  through  the  tube,  lift  it  from  the  table,  and  the 
lower  card  will  follow.  In  fact,  you  cannot  blow  it  off, 

INFERENCE, 


AUXILIARY   WORK. 


99 


Aux.  32.  Much  better  than  the  wooden  ball,  in  Exp. 
79,  is  one  of  pith  or  of  cork ;  but  still  better  are  the  "oak- 
galls  "  or  "  oak-apples  "  which  grow  upon  oak-leaves,  as 
the  result  of  the  sting  of  a  certain  species  of  gall-fly.  The 
oak-gall  after  becoming  ripe  has  a  hard  shell,  but  is  very 
light,  and  by  a  little  skill  can  be  kept  in  the  air  a  consid- 
erable distance  from  the  tube  for  nearly  a  minute.  The 
best  size  is  at  least  an. inch  in  diameter.  Of  course  a 
straight  tube  can  be  used  by  throwing  the  head  back,  and 
with  skill  the  tube  can  be  brought  down  till  it  is  more 
nearly  horizontal  than  perpendicular,  and  the  oak-galls 
still  kept  revolving  in  mid-air.  A  quill  toothpick,  cut 
square  at  the  outer  end,  makes  a  very  serviceable  tube 
for  this  and  several  other  air  experiments. 

Aux.  33.    Cut  or  break  off  the  neck  of  a  bottle  (a 
smoothed   edge    is  not   essential),   and   fit   it  with  cork 
and  tube  as  illustrated.     Hold  it  well  down 
over   one    of   the  small  wooden  balls,  and 
blow  through  the  tube.     The  ball  rises  into 
the  bottle-neck,  and  you  cannot  blow  it  out 
even  with  a  powerful  bellows.     Use  also  a 
marble.     A  glass  marble  shows  beautifully 
the  rotations  it  makes.     The  same  piece  of 
apparatus  may   be    made    with   a    common 
spool  by  cutting  out  a  cone-shaped  cavity  in  one  end,  but 
a  white  glass  bottle-neck  makes  a  much  prettier  piece. 

INFERENCE.  What  lifts  the  ball  against  the  strong  cur- 
rent of  air  ? 


Aux.  33. 


APPENDIX. 


DIRECTIONS    FOR    MAKING    AND    ADJUSTING     THE    THREE    CLASS 
PIECES  OF   APPARATUS. 

THE  barometer  (Exp.  81)  is  very  easily  made  and  set  up. 
The  two  glass  tubes  should  be  at  least  33  and  5  inches  in  length, 
and  better  be  about  36  and  10  inches,  as  then  the  instrument 
will  give  more  accurate  readings.  The  size  of  the  tubes  is 
not  material,  though  of  course  the  larger  the  bore,  the  more 
mercury  required.  We  use  tubing  about  £  inch  in  diaineter, 
with  a  bore  about  one-third  of  that.  The  glass  tubes  are 
connected  with  a  short  piece  of  rubber  tubing  (about  3  inches). 

The  short  tube,  for  greater  ease  in  filling,  should  be  fun- 
nelled, which  is  easily  done  by  the  aid  of  a  Bunsen  burner 
and  pencil  of  charcoal.  The  long  tube  is  closed  at  one  end 
by  holding  it  in  the  hottest  part  of  the  Bunsen  burner  blaze. 
(See  Aux.  Work.)  To  fill  the  barometer,  insert  a  fine  clean 
wire  the  entire  length  of  the  tubes.  Slowly  pour  in  the  mer- 
cury, and  the  wire  will  enable  the  air  to  escape.  Look  occa- 
sionally, however ;  and  if  a  small  bubble  of  air  is  detected, 
churn  with  the  wire  until  it  rises  to  the  surface  of  the  mer- 
cury. Fill  the  long  glass  and  the  rubber  tube,  withdraw  the 
wire,  reverse  the  long  tube,  and  put  the  barometer  in  its  per- 
manent place.  We  use  one  side  of  a  window-casing,  though 
it  may  be  tacked  to  a  narrow  4-foot  piece  of  board,  and  hung 
wherever  desired.  The  most  convenient  method  of  read- 
ing the  barometer  is  by  a  sliding  yard  or  metre  stick,  as 
shown  in  the  cut.  While  this  barometer  will  not  be  abso- 
100 


lOi 

lutely  accurate  (but  few  are)  on  account  of  a  small  amount  of 
confined  air,  it  will  answer  all  schoolroom  purposes,  better 
even  than  the  more  expensive  ones.  We  keep  our  own  make 
hanging  beside  one  of  the  most  expensive,  but  use  our  own 
almost  invariably.  In  making  and  setting  up  a  barometer, 
tubes  and  mercury  should  be  clean  and  dry. 

A  very  instructive  barometer,  which  gradually  changes  to 
a  "  Boyle's  Law  "  instrument,  may  be  made  with  short  pieces 
of  tubing;  and  we  earnestly  recommend  it  as  an  auxiliary  to 
EXP.  88.  To  make  it,  use,  in  place  of  the  long  tube,  two 
pieces  each  18  to  20  inches  in  length,  and  fasten  the  ends  as 
closely  together  as  possible  with  a  piece  of  rubber  tubing 
tightly  tied  or  wii'ed  on.  It  is  at  first  a  good  barometer,  but 
the  slow  leaking  in  of  air  from  day  to  day  through  the  pores 
of  the  rubber  makes  an  interesting  series  of  experiments  for 
the  application  of  facts  learned  in  EXP.  88.  To  test  experi- 
mentally the  correctness  of  the  application,  lay  the  "  jointed  " 
barometer  flat  on  the  table,  when  the  enclosed  air  will  be 
under  normal  pressure.  Ask  pupils  to  explain  the  difference 
in  air  pressure  upon  the  outside  of  the  rubber  joint,  and  mer- 
cury pressure  upon  the  inside. 

The  piece  for  EXP.  83  is  very  easily  made  of  tubing  of 
any  convenient  size.  If  of  very  small  size,  the  wire  is  needed 
in  filling,  as  with  the  barometer.  If  more  than  13.6  inches  of 
water  is  poured  in,  take  it  out  with  a  capillary  tube  or  with 
narrow  strips  of  blotting-paper.  Young  pupils  will  not  usu- 
ally detect  the  slight  variation  from  an  inch  in  the  mercury 
column  made  by  a  half-inch  more  or  less  of  water,  hence  it  is 
better  to  have  it  as  exact  as  possible. 

The  apparatus  for  EXP.  88  (Boyle's  Law  piece)  is  as 
easily  made  as  the  barometer,  but  requires  great  care  in  the 
selection  of  tubes,  and  still  greater  care  and  skill  in  filling  and 
setting  up.  It  may  be  made  with  the  upper  end  of  the  short 
glass  tube  closed  like  a  barometer,  or  left  open  and  provided 


J02  INDUCTIVE  PHYSICS. 

with  a  cap  of  rubber  and  glass  as  shown  in  the  cut.  The  first 
method  makes  an  instrument  that  is  much  more  satisfactory 
to  use,  but  somewhat  difficult  to  fill.  Select  a  9.5-inch  piece 
of  tubing  about  .25  inch  in  diameter,  taking  special  care  that 
the  bore  is  the  same  size  throughout.  Close  one  end  in  the 
Bunsen  burner  blaze,  and  by  means  of  a  short  piece  of  rubber 
tubing,  connect  the  other  end  with  a'small  glass  funnel,  easily 
made  of  a  piece  of  glass  tubing.  Select  a  glass  tube  nearly  or 
quite  twice  as  long  as  the  first,  with  a  bore  the  area  of  the 
cross-section  of  which  is  nearly  twice  that  of  the  first  tube, 
and  funnel  one  end  of  it.  Obtain  a  rubber  tube  with  bore  as 
nearly  as  possible  the  same  as  that  of  the  short  glass  tube. 
The  rubber  tube  should  be  firm  enough  not  to  stretch  much, 
if  any,  under  the  weight  of  the  mercury  with  which  it  is  filled  ; 
hence  the  best  quality  of  rubber  is  not  the  best  for  this  pur- 
pose. Take  a  strip  39  inches  in  length,  and  force  .5  inch  of 
it  over  the  small  end  of  the  long  glass  tube.  If  the  rubber 
tube  is  not  very  thick-walled,  it  should  be  strengthened  where 
it  is  stretched  over  the  short  glass  tube.  This  is  done  by  slip- 
ping over  the  end  of  it  a  one-  or  two-inch  piece  of  larger  rub- 
ber tubing .  before  the  glass  tube  is  inserted.  The  rubber  is 
stretched,  and  consequently  weakened,  more  at  the  end  of  the 
long  glass  tube ;  but  as  it  never  has  to  bear  a  pressure  of  mer- 
cury much  greater  than  outside  air  pressure,  it  does  not  need 
strengthening.  To  fill  the  short  tube,  use  the  wire  as  in  the 
barometer,  and  pour  in  mercury  till  it  measures  exactly  6.5 
inches  deep  after  the  wire  is  withdrawn,  leaving  3  inches  filled 
with  air.  Remove  the  funnel  and  rubber  connector,  and  lay 
the  tube  upon  the  table.  The  mercury  will  not  run  out.  Slip 
the  end  of  the  long  rubber  tube  just  barely  over  the  end  of  a 
short  piece  of  glass  tubing,  which  then  hang  in  a  tumbler  or 
small  wide-mouthed  bottle  standing  in  a  dinner-plate.  Let  the 
rubber  tube  lie  upon  the  table  with  long  glass  tube  at  the 
other  end,  fastened  in  an  upright  or  inclined  position.  Pour 


APPENDIX.  103 

in  mercury  till  the  rubber  tube  is  full,  and  it  is  running  out 
of  the  short  tube.  Be  very  sure  that  all  air  has  been  driven 
out  of  the  rubber  tube,  then  seize  it  between  thumb  and  finger 
close  to  the  short  tube,  and  close  it  tightly  ;  remove  it  from  the 
tube,  working  over  the  plate  to  catch  the  mercury  if  any  is 
spilled.  Now  comes  the  most  difficult  part  of  the  work.  The 
open  end  of  the  9.5-inch  tube  must  be  inserted  without  getting 
in  any  more  air,  then  the  rubber  tube  is  slipped  on  to  cover 
just  one-half  inch  of  the  glass  tube.  It  probably  will  cost 
you  several  trials.  It  did  me,  and  I  do  not  yet  always  suc- 
ceed the  first  time.  The  mercury  is  then  shaken  down,  and 
the  3  inches  of  air  got  into  the  upper  end  of  the  tube.  Fasten 
the  rubber  tube  tightly  to  the  short  glass  tube,  by  winding  it 
with  a  piece  of  copper  wire  (about  No.  18),  which  then  fasten 
by  twisting  with  pliers,  and  make  a  hook  or  loop  of  the  ends 
with  which  to  hang  the  tube.  Now,  holding  both  tubes  per- 
pendicular, raise  the  open  tube  till  the  mercury  in  it  is  30 
inches  above  that  in  the  closed  tube  (if  barometer  stands  at 
30  inches),  and  the  air  in  the  closed  tube  occupies  1.5  inches. 
The  mercury  should  show  but  a  fraction  of  an  inch  in  the 
long  tube  when  held  thus ;  when  such  is  the  case,  the  instru- 
ment is  ready  for  adjusting  to  the  wall  or  window-casing. 
One  side  of  a  window-casing  makes  a  good  place  for  it,  as  the 
rubber  tubing  filled  with  mercury  can  then  lie  upon  the  win- 
dow-sill when  the  instrument  is  not  in  use.  Drive  the  first 
nail  or  hook  for  the  long  tube  sp  that  it  will  hang  just  above 
the  window-sill,  and  a  nail  for  the  short  tube  where  it  will 
hang  with  both  mercury  surfaces  at  the  same  level.  If  the 
wire  loop  for  suspension  is  at  the  lower  end  of  the  short  tube, 
instead  of  the  upper  end  as  shown  in  the  cut,  a  hook,  or  two 
crossed  nails,  will  be  needed  at  a  higher  point  to  keep  it  in 
place. 

Elevate  the   open  tube  until  its  mercury  surface   is  15 
inches  above  that  in  the  closed  tube,  and  drive  a  nail  on 


104  INDUCTIVE  pnrsics. 

which  pupils  will  hang  the  tube  when  experimenting.  Do 
the  same  for  a  difference  of  30  inches.  Return  the  tube 
to  its  first  position,  and  drive  nails  for  the  short  tube  which 
will  carry  its  mercury  surface  7.5,  15,  and  20  inches  above 
the  other. 

The  following  is  a  better  way  to  fasten  the  tubes  where 
the  window-sill  does  not  project  much  beyond  the  casing,  and 
where  it  is  high  enough  from  the  floor  so  that  there  is  room 
to  lower  the  open  tube  till  the  mercury  sinks  in  the  short 
tube  to  the  end  of  the  rubber.  Fasten  as  above,  except  with 
the  tubes  near  the  front  edge  of  the  casing,  and  with  the  short 
tube  tacked  firmly  in  place ;  then,  instead  of  raising  it,  lower 
the  open  tube  for  the  last  three  readings. 

The  above  method  of  constructing  and  filling  this  appara- 
tus is  the  best  we  have  been  able  to  devise ;  but,  for  fear  some 
parties  may  find  the  task  of  filling  too  severe,  we  have  devised 
an  easier  method.  Leave  the  short  tube  open  at  the  upper 
end,  and  fasten  it  to  the  rubber  tube  before  filling.  Make  a 
cap  by  tightly  wiring  a  half-inch  piece  of  glass  rod  into  one 
end  of  an  inch  piece  of  rubber  tubing.  With  the  short  tube 
lacking  about  3  inches  of  being  full  of  mercury,  crowd  on 
this  cap  as  tightly  as  possible,  and  wire  it  tightly,  twisting 
the  wire  with  pliers  until  it  is  nearly  buried  in  the  rubber. 
Then,  if  there  is  not  exactly  3  inches  of  air  when  both  mer- 
cury surfaces  are  at  the  same  level,  raise  one  tube  or  the 
other  as  may  Joe  necessary  to  allow  air  to  be  forced  out  or  in 
through  the  rubber.  While  this  method  of  construction  has 
the  advantage  of  being  easy  to  fill,  it  has  the  disadvantage  of 
leaking  air  through  the  pores  of  the  rubber  every  time  it  is 
vised,  even  if  wiring  is  good  enough  to  prevent  its  leaking 
between  glass  and  rubber.  Hence  it  requires  constant  atten- 
tion to  keep  the  correct  amount  of  confined  air.  If,  however, 
it  is  not  left  hanging  long  at  either  extreme  of  increased  or 


APPENDIX.  105 

diminished  pressure,  it  does  not  change  volume  of  air  very 
rapidly. 

By  either  method  of  construction,  this  apparatus  is  by  far 
the  cheapest  one  yet  devised  for  anything  like  the  range  it 
gives.  Its  cost,  including  mercury,  should  fall  between  one 
and  two  dollars,  according  to  the  size  of  tubes  used  and 
consequent  amount  of  mercury  required. 


A  D  VER  TISEMENT. 


"100  IN  1   PHYSICAL   SCIENCE  APPARATUS." 

Apparatus  for  Bailey's  "  Inductive  Elementary  Physical 
Science  "  is  furnished  by  the  author  at  $3.00  a  set.  This 

Apparatus  is  accurately  made 
of  the  best  material,  is  well 
packed  in  boxes  (size  12  x  6  x 
3  inches)  suitable  for  school- 
room use,  and  with  decent 
usage  will  last  many  years. 
Each  box  contains  articles  1 
to  49  of  the  illustrated  list 
(pages  7-9),  and  is  sent  by  ex- 
press at  manufacturer's  risk. 
Articles  carelessly  broken  by 
pupils  are  replaced  at  their 
proportional  cost.  Prices  for 
Nos.  1,  2,  3, 13, 38,  and  others, 
sent  upon  application  to  per- 
sons desiring  to  make  their 
own  apparatus. 

Class  pieces  50,  51,  and 
52  will  be  furnished  only  to 
schools  using  this  course,  at 
the  low  price  of  $3.00  a  set, 
and  cost  of  boxing. 

Teachers'  sets  differ  from  pupil's  only  in  containing  three 
extra  pieces,  —  a  gas-jet  glass-cutter  (see  Aux.  WORK,  page 
73),  a  small  glass  funnel,  to  aid  careless  pupils  in  pouring 
mercury  into  stopper,  for  "  mercury  shower,"  EXP.  36,  and 
a  complete  Aux.  33.  This  set  will  be  sent  as  a  sample  upon 
receipt  of  order  accompanied  with  a  $3.00  check  or  P.  0. 
order  on  Station  B,  Boston. 

F.  H.  BAILED,  6  Marlboro  Street,  Boston. 
106 


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III.     Principles  and  Methods  of  Physical  Measurement,  Physical  Laws  and  Princi- 
ples, and  Mathematical  and  Physical  Tables.     $1.30. 

IV.     Appendix  for  the  use  of  Teachers,  including  examples  of  observation  and  re 
duction.    Part  IV  is  needed  by  students  only  when  working  without  a  teacher. 

Parts  I-III,  in  one  vol.,  $3.25.     Parts  I-IV,  in  one  vol.,  $4.00. 

Wllliams's  Modern  Petrography.  An  account  of  the  application  of  the  micro 
scope  to  the  study  of  geology.  Paper.  25  cts. 

For  elementary  works  see  our  list  of  books  in  Elementary  Science. 

D.    C.   HEATH   &   CO.,   PUBLISHERS. 

BOSTON.       NEW  YORK        CHICAGO. 


GEOGRAPHY  AND  MAPS. 


Heath's  Outline  Map  Of  the  United  States.  Invaluable  for  marking  territorial 
growth  and  for  the  graphic  representation  of  all  geographical  and  historical  matter.  Small 
(desk)  size,  2  cents  each ;  $1.50  per  hundred.  Intermediate  size,  30  cents  each.  Large 
size,  50  cts. 

Historical  Outline  Map  Of  Europe.  12  x  18  inches,  on  bond  paper,  in  black  outline. 
3  cents  each  ;  per  hundred,  $2.25. 

Jackson's  Astronomical  Geography.  Simple  enough  for  grammar  schools.  Used 
for  a  brief  course  in  high  school.  40  cts. 

Map  Of  Ancient  History.  Outline  for  recording  historical  growth  and  statistics  (141 
17  in.),  3  cents  each;  per  100,  $2.25. 

Nichols'  Topics  in  Geography.  A  guide  for  pupils'  use  from  the  primary  through 
the  eighth  grade.  65  cts. 

Picturesque  Geography.  12  lithograph  plates,  15  x  20  inches,  and  pamphlet  describing 
their  use.  Per  set,  $3.00;  mounted,  $5.00. 

Progressive  Outline  Maps:  United  States,  *World  on  Mercator's  Projection  (12  x 
20  in.) ;  North  America,  South  America,  Europe,  'Central  and  Western  Europe,  Africa. 
Asia,  Australia,  'British  Isles,  'England,  'Greece,  'Italy,  New  England,  Middle  Atlan- 
tic States,  Southern  States,  Southern  States  —  western  section,  Central  Eastern  States. 
Central  Western  States,  Pacific  States,  New  York,  Ohio,  The  Great  Lakes,  Washington 
(State),  'Palestine  (each  10  x  12  in.).  For  the  graphic  representation  by  the  pupil  of 
geography,  geology,  history,  meteorology,  economics,  and  statistics  of  all  kinds.  2  cents 
each;  per  hundred,  $1.50. 
Those  marked  with  Star  (')  are  also  printed  in  black  outline  for  use-in  teaching  history. 

Redway's  Manual  Of  Geography.  I.  Hints  to  Teachers;  II.  Modern  Facts  and 
Ancient  Fancies.  65  cts. 

Redway's  Reproduction  of  Geographical  Forms.    I.  Sand  and  clay- Modelling; 

II.  Map  Drawing  and  Projection.     Paper.     30  cts. 

Roney's  Student's  Outline  Map  of  England.    For  use  in  English  History  and 

Literature,  to  be  filled  in  by  pupils.     5  cts. 

TrOtter'S  Lessons  in  the  New  Geography.  Treats  geography  from  the  humac 
point  of  view.  Adapted  for  use  as  a  text-book  or  as  a  reader,  ji.oo 


D.   C.    HEATH    &   CO.,   PUBLISHERS. 

BOSTON.        NEW  YORK.        CHICAGO. 


DRAWING  AND  MANUAL  TRAINING. 


Anthony's  Mechanical  Drawing.     98  pages  of  text,  and  32  folding  plates.    $1.50. 
Anthony's  Machine  Drawing.     50  pages  of  text,  and  15  folding  plates.    $1.25. 
Daniels'  Freehand  Lettering.     34  pages  of  text,  and  13  folding  plates.    85  cts. 
Lunt's  Brushwork  for  Kindergarten  and  Primary  School.     18  lesson-cards 

in  colors,  with  teacher's  pamphlet,  in  envelope.     30  cts. 

Johnson's  Progressive  Lessons  in  Needlework.     Explains  needlework  from  its 

rudiments  and  gives  with  illustrations  full  directions  for  work   during  six  grades.     117 
pages.     Square  8vo.     Cloth,  $1.00.     Boards,  60  cts. 

Seidel's  Industrial  Instruction  (Smith).  A  refutation  of  all  objections  raised  against 
industrial  instruction.  170  pages,  go  cts. 

Thompson's  Educational  and  Industrial  Drawing. 

Primary  Free-Hand  Series  (Nos.  1-4).     Each  No.,  per  doz.,  $1.00. 
Primary  Free-Hand  Manual.     114  pages.     Paper.     40  cts. 
Advanced  Free-Hand  Series  (Nos.  5-8).     Each  No.,  per  doz.,  $  1.5*, 
Model  and  Object  Series  (Nos.  1-3).     Each  No.,  per  doz.,  $1.75. 
Model  and  Object  Manual.     84  pages.     Paper.     35  cts. 
./Esthetic  Series  (Nos.  1-6).     Each  No.,  per  doz.,  $1.50. 
jEsthetic  Manual.     174  pages.     Paper.     60  cts. 
Mechanical  Series  (Nos.  1-6).     Each  No.,  per  doz.,  £2.00. 
Mechanical  Manual.     172  pages.     Paper.     75  cts. 

Thompson's  Manual  Training,  NO.  I.  Treats  of  Clay  Modelling,  Stick  and 
Tablet  Laying,  Paper  Folding  and  Cutting,  Color,  and  Construction  of  Geometrical 
Solids.  Illustrated.  66  pages.  Large  8vo.  Paper.  30  cts. 

Thompson's  Manual  Training,  NO.  2.  Treats  of  Mechanical  Drawing,  Clay. 
Modelling  in  Relief,  Color,  Wood  Carving,  Paper  Cutting  and  Pasting.  Illustrated. 
70  pp.  Large  8vo.  Paper.  30  cts. 

Waldo's  Descriptive  Geometry.  A  large  number  of  problems  systematically  ar- 
ranged, with  suggestions.  85  pages.  90  cts. 

Whitaker's  HOW  to  Use  Wood  Working  Tools.  Lessons  in  the  uses  of  the 
universal  tools :  the  hammer,  knife,  plane,  rule,  chalk-line,  square,  gauge,  chisel,  saw, 
and  auger.  104  pages.  60  cts. 

Woodward's  Manual  Training  School.  Its  aims,  methods,  and  results;  with 
detailed  courses  of  instruction  in  shop-work.  Fully  illustrated.  374  pages.  Octavo.  $2.00. 

Sent  postpaid  by  mail  on  receipt  of  price. 


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BOSTON.        NEW  YORK.        CHICAGO. 


BUSINESS. 


Seavy's  Practical  Business  Bookkeeping.     All  needless  discussion  is  carefully 

avoided.     Only  such  explanations  are  given  as  are  essential  to   preparation  for  actual 
business  duties.     Half  leather.    $1.55. 

Blanks  to  Accompany  Seavy's  Practical  Business  Bookkeeping.    Per  set  of 

three,  70  cts. 

Seavy's  Manual  Of  Business  Transactions.  Contains  transactions  for  practice, 
together  with  instructions  and  references  to  the  author's  Bookkeeping.  45  cts. 

Shaw's  Practice  Book  of  Business  Forms  and  Elementary  Bookkeeping. 

Treats  of  the  best  methods  of  keeping  simple  accounts  and  furnishes  a  necessary  knowl- 
edge of  ordinary  business  forms.     Flexible  boards.     70  cts. 

Weed's   Business   Law.      A  brief  statement  of  the  laws  that  govern  business.     Ji.io. 

The  Natural  System  of  Vertical  Writing.     (Newlands  and  Row).  The  special 

excellences  of  this  system  are  simplicity,  legibility,  and  the  ease  with  which  it  can  b« 
learned.     Six  books,  each,  per  dozen,  75  cts.     Teacher's  manual,  25  cts. 

The  Volpenna  Pens.  Specially  made  for  vertical  writing,  but  also  adapted  to  rapid 
business  writing.  Volpenna  A,  coarse  points.  Volpenna  B,  medium  points.  Each,  per 
gross,  60  cts. 

Haaren's  Writing  BOOkS.  Slanting  copies  of  great  beauty.  Tracing  course,  two 
books,  per  dozen,  72  cts.  Primary  course,  four  books,  per  dozen,  72  cts.  Grammar 
course,  four  books,  per  dozen,  96  cts. 

The  New  Arithmetic.      An  excellent  review  and  practice  book.     230  pages.     75  cts. 


D.   C.   HEATH   &   CO.,   PUBLISHERS, 

BOSTON.        NEW  YORK.        CHICAGO. 


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